diff --git a/apps/demos/scenery/scenes/ingame.c b/apps/demos/scenery/scenes/ingame.c
index b2f8d4d..29481d9 100644
--- a/apps/demos/scenery/scenes/ingame.c
+++ b/apps/demos/scenery/scenes/ingame.c
@@ -53,14 +53,16 @@ static float heightmap[TERRAIN_DISTANCE][TERRAIN_DISTANCE];
 /* else if length(v(o) + (F(o)/m)*t) <= (f(k)*x(n)*t), v(o) = 0 */
 /*     else, F = -unit(v(o)*f(k)*x(n)) */
 
-#define VEHICLE_MASS 150.0f
+#define VEHICLE_MASS 200.0f
 #define VEHICLE_LENGTH 3.0f
 #define VEHICLE_WIDTH 1.7f
 #define VEHICLE_HEIGHT 1.3f
 /* spring constant */
-#define VEHICLE_SPRING_K 80000.0f
+#define VEHICLE_SPRING_K 20000.0f
+#define VEHICLE_SPRING_GK 60000.0f
 /* damping constant */
 #define VEHICLE_SPRING_C 500.0f
+#define VEHICLE_SPRING_GC 100.0f
 #define VEHICLE_FRICTION_S 1000.0f
 #define VEHICLE_FRICTION_K 100.0f
 
@@ -143,10 +145,10 @@ static void process_vehicle(SceneIngame *scn) {
         float const h = height_at(scn, (Vec2){ p.x, p.z });
         if (h >= p.y) {
             /* wheel processing */
-            if (i == 0 || i == 3) {
+            if (i == 0 || i == 3 || i == 4 || i == 7) {
                 if (scn->camera_mode == 2 && input_action_pressed("player_forward")) {
                     Vec3 const dir = i == 0 ? vec3_sub(vbp[0], vbp[1]) : vec3_sub(vbp[3], vbp[2]);
-                    Facc[i] = vec3_add(Facc[i], vec3_scale(vec3_norm(dir), 18000));
+                    Facc[i] = vec3_add(Facc[i], vec3_scale(vec3_norm(dir), 15000));
                 }
             }
 
@@ -154,7 +156,9 @@ static void process_vehicle(SceneIngame *scn) {
             Vec3 const n = normal_at(scn, (Vec2){ p.x, p.z });
             float const xn = (h - p.y) * n.y;
             float const vn = vec3_dot(v, n);
-            Vec3 const Fn = vec3_scale(n, -VEHICLE_SPRING_K * xn - VEHICLE_SPRING_C * vn);
+            Vec3 const Fn = vec3_scale(n, -VEHICLE_SPRING_GK * xn - VEHICLE_SPRING_GC * vn);
+            draw_line_3d(vbp[i], vec3_sub(vbp[i], Fn), 1, (Color){255,255,0,255});
+            Facc[i] = vec3_sub(Facc[i], Fn);
 
             /* friction force, perpendicular to normal force */
             Vec3 const vo = vec3_sub(v, vec3_scale(n, vn));
@@ -162,7 +166,7 @@ static void process_vehicle(SceneIngame *scn) {
             Vec3 Fo = vec3_sub(Facc[i], vec3_scale(n, vec3_dot(Facc[i], n)));
             /* portion of total force along the surface */
             float const Fol = vec3_length(Fo);
-            float const fkxn = VEHICLE_FRICTION_K * xn * 50;
+            float const fkxn = VEHICLE_FRICTION_K * xn;
             /* at rest, might want to start moving */
             if (fabsf(0.0f - vol) <= 0.0001f) {
                 /* cannot overcome static friction, force along the surface is zeroed */
@@ -171,26 +175,18 @@ static void process_vehicle(SceneIngame *scn) {
                 else Fo = vec3_sub(Fo, vec3_scale(vec3_norm(Fo), fkxn));
             /* not at rest, stop accelerating along the surface */
             } else if (vol + (Fol / VEHICLE_MASS) * ctx.frame_duration <= fkxn * ctx.frame_duration) {
-                log_info("test 1");
-                // vbv[i] = vec3_sub(vbp[i], vo);
-                vbv[i] = (Vec3){0};
+                vbv[i] = vec3_sub(vbv[i], vo);
             /* just apply friction */
             } else {
-                log_info("test 2, depth: %f", xn);
-                Fo = vec3_add(Fo, vec3_scale(vec3_norm(vo), -fkxn * 100));
+                Fo = vec3_add(Fo, vec3_scale(vec3_norm(vo), -fkxn * 1000));
             }
-
-            /* total force, after ground interaction */
-            Vec3 const Ft = vec3_add(vec3_scale(Fn, -1), Fo);
-            Vec3 vd = vec3_scale(vec3_scale(Ft, (1.0f / VEHICLE_MASS)), ctx.frame_duration);
-            vbv[i] = vec3_add(vbv[i], vd);
-            vbp[i] = vec3_add(vbp[i], vec3_scale(vbv[i], ctx.frame_duration));
-        } else {
-            /* in air */
-            Vec3 vd = vec3_scale(vec3_scale(Facc[i], (1.0f / VEHICLE_MASS)), ctx.frame_duration);
-            vbv[i] = vec3_add(vbv[i], vd);
-            vbp[i] = vec3_add(vbp[i], vec3_scale(vbv[i], ctx.frame_duration));
+            Facc[i] = vec3_add(Facc[i], Fo);
         }
+
+        /* in air */
+        Vec3 vd = vec3_scale(vec3_scale(Facc[i], (1.0f / VEHICLE_MASS)), ctx.frame_duration);
+        vbv[i] = vec3_add(vbv[i], vd);
+        vbp[i] = vec3_add(vbp[i], vec3_scale(vbv[i], ctx.frame_duration));
     }
 }
 
@@ -260,10 +256,10 @@ static Vec3 normal_at(SceneIngame *scn, Vec2 position) {
     float const height1 = heightmap[x + 1][y];
     float const height2 = heightmap[x][y + 1];
 
-    Vec3 const a = { .x = 1, .y = height0 - height1, .z = 0 };
+    Vec3 const a = { .x = -1, .y = height0 - height1, .z = 0 };
     Vec3 const b = { .x = 0, .y = height0 - height2, .z = -1 };
 
-    return vec3_norm(vec3_cross(a, b));
+    return vec3_scale(vec3_norm(vec3_cross(a, b)), -1);
 }
 
 /* TODO: don't operate on triangles, instead interpolate on quads */
@@ -349,7 +345,7 @@ static void generate_terrain(SceneIngame *scn) {
             float height = stb_perlin_noise3((float)x * TERRAIN_FREQUENCY, (float)y * TERRAIN_FREQUENCY, 0, 0, 0, 0) * 3 - 1;
             height += stb_perlin_noise3((float)x * TERRAIN_FREQUENCY / 10, (float)y * TERRAIN_FREQUENCY / 10, 0, 0, 0, 0) * 20 - 1;
 
-            heightmap[lx][ly] = height;
+            heightmap[lx][ly] = height * 0.3f;
         }
     }