diff --git a/source/egg/math/Quat.hh b/source/egg/math/Quat.hh
index f4a22a83..4052cb92 100644
--- a/source/egg/math/Quat.hh
+++ b/source/egg/math/Quat.hh
@@ -63,16 +63,16 @@ struct Quatf {
         return *this = *this * q;
     }
 
-    bool operator==(const Quatf &rhs) const {
+    [[nodiscard]] bool operator==(const Quatf &rhs) const {
         return w == rhs.w && v == rhs.v;
     }
 
-    bool operator!=(const Quatf &rhs) const {
+    [[nodiscard]] bool operator!=(const Quatf &rhs) const {
         return !(*this == rhs);
     }
 
     /// @brief A conversion function that allows for string representation of a quaternion.
-    explicit operator std::string() const {
+    [[nodiscard]] explicit operator std::string() const {
         return std::format("[0x{:08X}, 0x{:08X}, 0x{:08X}, 0x{:08X}] | [{}, {}, {}, {}]", f2u(v.x),
                 f2u(v.y), f2u(v.z), f2u(w), v.x, v.y, v.z, w);
     }
@@ -82,33 +82,33 @@ struct Quatf {
     void makeVectorRotation(const Vector3f &from, const Vector3f &to);
 
     /// @brief Computes \f$conj(a+bi+cj+dk) = a-bi-cj-dk\f$
-    Quatf conjugate() const {
+    [[nodiscard]] Quatf conjugate() const {
         return Quatf(w, -v);
     }
 
-    Vector3f rotateVector(const Vector3f &vec) const;
-    Vector3f rotateVectorInv(const Vector3f &vec) const;
-    Quatf slerpTo(const Quatf &q2, f32 t) const;
+    [[nodiscard]] Vector3f rotateVector(const Vector3f &vec) const;
+    [[nodiscard]] Vector3f rotateVectorInv(const Vector3f &vec) const;
+    [[nodiscard]] Quatf slerpTo(const Quatf &q2, f32 t) const;
 
     /// @addr{0x8023A138}
     /// @brief Computes \f$this \cdot this = w^2 + x^2 + y^2 + z^2\f$
-    f32 squaredNorm() const {
+    [[nodiscard]] f32 squaredNorm() const {
         return w * w + v.squaredLength();
     }
 
-    f32 norm() const {
+    [[nodiscard]] f32 norm() const {
         return Mathf::sqrt(squaredNorm());
     }
 
     /// @brief Computes \f$this \cdot rhs = w \times rhs.w + x \times rhs.x + y \times rhs.y + z
     /// \times rhs.z\f$
-    f32 dot(const Quatf &q) const {
+    [[nodiscard]] f32 dot(const Quatf &q) const {
         return w * q.w + v.dot(q.v);
     }
 
     void setAxisRotation(f32 angle, const Vector3f &axis);
-    Quatf multSwap(const Vector3f &v) const;
-    Quatf multSwap(const Quatf &q) const;
+    [[nodiscard]] Quatf multSwap(const Vector3f &v) const;
+    [[nodiscard]] Quatf multSwap(const Quatf &q) const;
 
     void read(Stream &stream);
 
diff --git a/source/egg/math/Vector.hh b/source/egg/math/Vector.hh
index 197e8205..b0cabd36 100644
--- a/source/egg/math/Vector.hh
+++ b/source/egg/math/Vector.hh
@@ -154,11 +154,11 @@ struct Vector3f {
         return *this = *this / scalar;
     }
 
-    bool operator==(const Vector3f &rhs) const {
+    [[nodiscard]] bool operator==(const Vector3f &rhs) const {
         return x == rhs.x && y == rhs.y && z == rhs.z;
     }
 
-    bool operator!=(const Vector3f &rhs) const {
+    [[nodiscard]] bool operator!=(const Vector3f &rhs) const {
         return !(*this == rhs);
     }
 
diff --git a/source/game/field/CourseColMgr.hh b/source/game/field/CourseColMgr.hh
index 320fab2c..f08bec6f 100644
--- a/source/game/field/CourseColMgr.hh
+++ b/source/game/field/CourseColMgr.hh
@@ -92,7 +92,7 @@ public:
     }
     /// @endGetters
 
-    static void *LoadFile(const char *filename);
+    [[nodiscard]] static void *LoadFile(const char *filename);
 
     static CourseColMgr *CreateInstance();
     static void DestroyInstance();
diff --git a/source/game/field/ObjectCollisionBase.hh b/source/game/field/ObjectCollisionBase.hh
index 97224514..6dd7df42 100644
--- a/source/game/field/ObjectCollisionBase.hh
+++ b/source/game/field/ObjectCollisionBase.hh
@@ -28,8 +28,8 @@ public:
 
     virtual void transform(const EGG::Matrix34f &mat, const EGG::Vector3f &scale,
             const EGG::Vector3f &speed) = 0;
-    virtual const EGG::Vector3f &getSupport(const EGG::Vector3f &v) const = 0;
-    virtual f32 getBoundingRadius() const = 0;
+    [[nodiscard]] virtual const EGG::Vector3f &getSupport(const EGG::Vector3f &v) const = 0;
+    [[nodiscard]] virtual f32 getBoundingRadius() const = 0;
 
     bool check(ObjectCollisionBase &rhs, EGG::Vector3f &distance);
 
@@ -37,12 +37,12 @@ protected:
     EGG::Vector3f m_translation;
 
 private:
-    bool enclosesOrigin(const GJKState &state, u32 idx) const;
+    [[nodiscard]] bool enclosesOrigin(const GJKState &state, u32 idx) const;
     void FUN_808350e4(GJKState &state, EGG::Vector3f &v) const;
     bool getNearestSimplex(GJKState &state, EGG::Vector3f &v) const;
     void getNearestPoint(GJKState &state, u32 idx, EGG::Vector3f &v0, EGG::Vector3f &v1) const;
-    bool FUN_808357e4(const GJKState &state, u32 idx) const;
-    bool inSimplex(const GJKState &state, const EGG::Vector3f &v) const;
+    [[nodiscard]] bool FUN_808357e4(const GJKState &state, u32 idx) const;
+    [[nodiscard]] bool inSimplex(const GJKState &state, const EGG::Vector3f &v) const;
     void getNearestPoint(const GJKState &state, u32 idx, EGG::Vector3f &v) const;
     void calcSimplex(GJKState &state) const;
 
diff --git a/source/game/field/ObjectCollisionConvexHull.hh b/source/game/field/ObjectCollisionConvexHull.hh
index fc3482d6..fcad0421 100644
--- a/source/game/field/ObjectCollisionConvexHull.hh
+++ b/source/game/field/ObjectCollisionConvexHull.hh
@@ -12,7 +12,7 @@ public:
 
     void transform(const EGG::Matrix34f &mat, const EGG::Vector3f &scale,
             const EGG::Vector3f &speed) override;
-    const EGG::Vector3f &getSupport(const EGG::Vector3f &v) const override;
+    [[nodiscard]] const EGG::Vector3f &getSupport(const EGG::Vector3f &v) const override;
 
     /// @addr{0x807F957C}
     f32 getBoundingRadius() const override {
diff --git a/source/game/field/ObjectCollisionCylinder.hh b/source/game/field/ObjectCollisionCylinder.hh
index b25dc7e6..bc882315 100644
--- a/source/game/field/ObjectCollisionCylinder.hh
+++ b/source/game/field/ObjectCollisionCylinder.hh
@@ -13,12 +13,12 @@ public:
             const EGG::Vector3f &speed) override;
 
     /// @addr{0x8083618C}
-    const EGG::Vector3f &getSupport(const EGG::Vector3f &v) const override {
+    [[nodiscard]] const EGG::Vector3f &getSupport(const EGG::Vector3f &v) const override {
         return m_top.dot(v) > m_bottom.dot(v) ? m_top : m_bottom;
     }
 
     /// @addr{0x80836498}
-    f32 getBoundingRadius() const override {
+    [[nodiscard]] f32 getBoundingRadius() const override {
         return m_worldRadius;
     }
 
diff --git a/source/game/field/ObjectCollisionKart.hh b/source/game/field/ObjectCollisionKart.hh
index 7a9049bd..a67b0d32 100644
--- a/source/game/field/ObjectCollisionKart.hh
+++ b/source/game/field/ObjectCollisionKart.hh
@@ -20,8 +20,8 @@ public:
 
     size_t checkCollision(const EGG::Matrix34f &mat, const EGG::Vector3f &v);
 
-    static EGG::Vector3f GetHitDirection(u16 objKartHit);
-    static constexpr std::span<const EGG::Vector3f> GetVehicleVertices(Vehicle vehicle);
+    [[nodiscard]] static EGG::Vector3f GetHitDirection(u16 objKartHit);
+    [[nodiscard]] static constexpr std::span<const EGG::Vector3f> GetVehicleVertices(Vehicle vehicle);
 
 private:
     ObjectCollisionConvexHull *m_hull;
diff --git a/source/game/field/ObjectCollisionSphere.hh b/source/game/field/ObjectCollisionSphere.hh
index 0e5fe7f9..9d946307 100644
--- a/source/game/field/ObjectCollisionSphere.hh
+++ b/source/game/field/ObjectCollisionSphere.hh
@@ -11,10 +11,10 @@ public:
 
     void transform(const EGG::Matrix34f &mat, const EGG::Vector3f &scale,
             const EGG::Vector3f &speed) override;
-    const EGG::Vector3f &getSupport(const EGG::Vector3f &v) const override;
+    [[nodiscard]] const EGG::Vector3f &getSupport(const EGG::Vector3f &v) const override;
 
     /// @addr{0x80836B54}
-    f32 getBoundingRadius() const override {
+    [[nodiscard]] f32 getBoundingRadius() const override {
         return m_scaledRadius;
     }
 
diff --git a/source/game/field/ObjectFlowTable.hh b/source/game/field/ObjectFlowTable.hh
index 97c5f832..e4ab8eed 100644
--- a/source/game/field/ObjectFlowTable.hh
+++ b/source/game/field/ObjectFlowTable.hh
@@ -46,7 +46,7 @@ public:
     ObjectFlowTable(const char *filename);
     ~ObjectFlowTable();
 
-    const SObjectCollisionSet *set(s16 slot) const {
+    [[nodiscard]] const SObjectCollisionSet *set(s16 slot) const {
         return slot == -1 ? nullptr : slot < m_count ? &m_sets[slot] : nullptr;
     }
 
diff --git a/source/game/field/ObjectHitTable.hh b/source/game/field/ObjectHitTable.hh
index 6fb509c9..389f681f 100644
--- a/source/game/field/ObjectHitTable.hh
+++ b/source/game/field/ObjectHitTable.hh
@@ -13,8 +13,8 @@ public:
     ObjectHitTable(const char *filename);
     ~ObjectHitTable();
 
-    Kart::Reaction reaction(s16 i) const;
-    s16 slot(ObjectId id) const;
+    [[nodiscard]] Kart::Reaction reaction(s16 i) const;
+    [[nodiscard]] s16 slot(ObjectId id) const;
 
 private:
     s16 m_count;
diff --git a/source/game/kart/KartHalfPipe.hh b/source/game/kart/KartHalfPipe.hh
index d11244c9..205698b5 100644
--- a/source/game/kart/KartHalfPipe.hh
+++ b/source/game/kart/KartHalfPipe.hh
@@ -22,7 +22,7 @@ public:
     void end(bool boost);
 
     /// @addr{0x80574108}
-    static consteval f32 TerminalVelocity() {
+    [[nodiscard]] static consteval f32 TerminalVelocity() {
         return 65.0f;
     }
 
diff --git a/source/game/kart/KartMove.hh b/source/game/kart/KartMove.hh
index 3e09767b..03f326fe 100644
--- a/source/game/kart/KartMove.hh
+++ b/source/game/kart/KartMove.hh
@@ -86,7 +86,7 @@ public:
     bool calcZipperCollision(f32 radius, f32 scale, EGG::Vector3f &pos, EGG::Vector3f &upLocal,
             const EGG::Vector3f &prevPos, Field::CourseColMgr::CollisionInfo *colInfo,
             Field::KCLTypeMask *maskOut, Field::KCLTypeMask flags) const;
-    f32 calcSlerpRate(f32 scale, const EGG::Quatf &from, const EGG::Quatf &to) const;
+    [[nodiscard]] f32 calcSlerpRate(f32 scale, const EGG::Quatf &from, const EGG::Quatf &to) const;
     virtual void calcVehicleRotation(f32 turn);
     virtual void hop();
     virtual void onHop() {}
@@ -102,12 +102,12 @@ public:
     }
 
     /// @addr{0x8058758C}
-    virtual bool canWheelie() const {
+    [[nodiscard]] virtual bool canWheelie() const {
         return false;
     }
 
     /// @addr{0x8057DA18}
-    virtual bool canHop() const {
+    [[nodiscard]] virtual bool canHop() const {
         if (!state()->isHopStart() || !state()->isTouchingGround()) {
             return false;
         }
@@ -120,7 +120,7 @@ public:
     }
 
     /// @addr{0x8057EA94}
-    bool canStartDrift() const {
+    [[nodiscard]] bool canStartDrift() const {
         constexpr f32 MINIMUM_DRIFT_THRESOLD = 0.55f;
 
         return m_speed > MINIMUM_DRIFT_THRESOLD * m_baseSpeed;
diff --git a/source/game/kart/KartReject.hh b/source/game/kart/KartReject.hh
index 98b82ed8..5a7fc35b 100644
--- a/source/game/kart/KartReject.hh
+++ b/source/game/kart/KartReject.hh
@@ -13,7 +13,7 @@ public:
     void reset();
 
     void calcRejectRoad();
-    bool calcRejection();
+    [[nodiscard]] bool calcRejection();
 
 private:
     f32 m_rejectSign;
diff --git a/source/game/system/TimerManager.hh b/source/game/system/TimerManager.hh
index 9f820da3..6c037895 100644
--- a/source/game/system/TimerManager.hh
+++ b/source/game/system/TimerManager.hh
@@ -11,7 +11,7 @@ struct Timer {
     Timer(u32 data);
     ~Timer();
 
-    std::strong_ordering operator<=>(const Timer &rhs) const {
+    [[nodiscard]] std::strong_ordering operator<=>(const Timer &rhs) const {
         if (auto cmp = min <=> rhs.min; cmp != 0) {
             return cmp;
         }
@@ -27,11 +27,11 @@ struct Timer {
         return valid <=> rhs.valid;
     }
 
-    bool operator==(const Timer &rhs) const = default;
-    bool operator!=(const Timer &rhs) const = default;
+    [[nodiscard]] bool operator==(const Timer &rhs) const = default;
+    [[nodiscard]] bool operator!=(const Timer &rhs) const = default;
 
     /// @addr{0x807EE860}
-    Timer operator-(const Timer &rhs) const {
+    [[nodiscard]] Timer operator-(const Timer &rhs) const {
         s16 addMin = 0;
         s16 addSec = 0;
 
@@ -57,7 +57,7 @@ struct Timer {
         return Timer(newMin, newSec, newMs);
     }
 
-    Timer operator+(f32 ms) const {
+    [[nodiscard]] Timer operator+(f32 ms) const {
         s16 addMin = 0;
         s16 addSec = 0;
 
diff --git a/source/game/system/map/MapdataCannonPoint.hh b/source/game/system/map/MapdataCannonPoint.hh
index 41ebeb2c..924efba1 100644
--- a/source/game/system/map/MapdataCannonPoint.hh
+++ b/source/game/system/map/MapdataCannonPoint.hh
@@ -21,19 +21,19 @@ public:
     void read(EGG::Stream &stream);
 
     /// @beginGetters
-    const EGG::Vector3f &pos() const {
+    [[nodiscard]] const EGG::Vector3f &pos() const {
         return m_pos;
     }
 
-    const EGG::Vector3f &rot() const {
+    [[nodiscard]] const EGG::Vector3f &rot() const {
         return m_rot;
     }
 
-    u16 id() const {
+    [[nodiscard]] u16 id() const {
         return m_id;
     }
 
-    s16 parameterIdx() const {
+    [[nodiscard]] s16 parameterIdx() const {
         return m_parameterIdx;
     }
     /// @endGetters
diff --git a/source/game/system/map/MapdataGeoObj.hh b/source/game/system/map/MapdataGeoObj.hh
index 98010fdf..d6ec14cc 100644
--- a/source/game/system/map/MapdataGeoObj.hh
+++ b/source/game/system/map/MapdataGeoObj.hh
@@ -22,23 +22,23 @@ public:
     void read(EGG::Stream &stream);
 
     /// @beginGetters
-    u16 id() const {
+    [[nodiscard]] u16 id() const {
         return m_id;
     }
 
-    const EGG::Vector3f &pos() const {
+    [[nodiscard]] const EGG::Vector3f &pos() const {
         return m_pos;
     }
 
-    const EGG::Vector3f &rot() const {
+    [[nodiscard]] const EGG::Vector3f &rot() const {
         return m_rot;
     }
 
-    const EGG::Vector3f &scale() const {
+    [[nodiscard]] const EGG::Vector3f &scale() const {
         return m_scale;
     }
 
-    u16 presenceFlag() const {
+    [[nodiscard]] u16 presenceFlag() const {
         return m_presenceFlag;
     }
     /// @endGetters
diff --git a/source/host/KReplaySystem.hh b/source/host/KReplaySystem.hh
index 29a4fadf..6afc74e2 100644
--- a/source/host/KReplaySystem.hh
+++ b/source/host/KReplaySystem.hh
@@ -15,7 +15,7 @@ public:
     static KReplaySystem *CreateInstance();
     static void DestroyInstance();
 
-    static KReplaySystem *Instance() {
+    [[nodiscard]] static KReplaySystem *Instance() {
         return static_cast<KReplaySystem *>(s_instance);
     }
 
@@ -27,12 +27,12 @@ private:
     KReplaySystem(KReplaySystem &&) = delete;
     ~KReplaySystem() override;
 
-    bool calcEnd() const;
+    [[nodiscard]] bool calcEnd() const;
     void reportFail(const std::string &msg) const;
 
-    bool success() const;
-    s32 getDesyncingTimerIdx() const;
-    DesyncingTimerPair getDesyncingTimer(s32 i) const;
+    [[nodiscard]] bool success() const;
+    [[nodiscard]] s32 getDesyncingTimerIdx() const;
+    [[nodiscard]] DesyncingTimerPair getDesyncingTimer(s32 i) const;
 
     static void OnInit(System::RaceConfig *config, void *arg);
 
diff --git a/source/host/KTestSystem.hh b/source/host/KTestSystem.hh
index f7ad9a8d..a215a34f 100644
--- a/source/host/KTestSystem.hh
+++ b/source/host/KTestSystem.hh
@@ -20,7 +20,7 @@ public:
     static KTestSystem *CreateInstance();
     static void DestroyInstance();
 
-    static KTestSystem *Instance() {
+    [[nodiscard]] static KTestSystem *Instance() {
         return static_cast<KTestSystem *>(s_instance);
     }
 
@@ -118,13 +118,13 @@ private:
     bool popTestCase();
 
     bool calcTest();
-    TestData findCurrentFrameEntry();
+    [[nodiscard]] TestData findCurrentFrameEntry();
     void testFrame(const TestData &data);
 
     bool runTest();
     void writeTestOutput() const;
 
-    const TestCase &getCurrentTestCase() const;
+    [[nodiscard]] const TestCase &getCurrentTestCase() const;
 
     static void OnInit(System::RaceConfig *config, void *arg);
 
diff --git a/source/host/Option.hh b/source/host/Option.hh
index f3f6dd65..923dc3fe 100644
--- a/source/host/Option.hh
+++ b/source/host/Option.hh
@@ -15,7 +15,7 @@ enum class EOption {
 
 namespace Option {
 
-std::optional<EOption> CheckFlag(const char *arg);
+[[nodiscard]] std::optional<EOption> CheckFlag(const char *arg);
 
 } // namespace Option
 } // namespace Host