games: 60 fps rendering loop + smoother Snake controls

Both games now render at 60 fps independent of the game-logic step rate:
the main loop caps select() at one frame (16 ms) so the screen updates
smoothly even when gravity/snake steps are slow, and renders every frame
or whenever state changed.

Snake: replaced the turn queue with a single buffered direction (latest
keypress wins) so rapid key presses don't queue up and misfire. Base speed
set to 100 px/sec (~90 ms per step) for controllable, responsive play.
Progressive difficulty (+1 px/sec per 5 food) and edge wrap are unchanged.

src/games/snake.cpp

@@ -102,13 +102,12 @@ static State state = PLAYING;
 static int snake[COLS * ROWS][2]; // x,y per segment (0 = tail)
 static int snakelen = 4;
 static int dirx = 1, diry = 0;     // current direction
-static int tqx[4], tqy[4];         // queued pending turns (rapid presses not lost)
+static int ndirx = 1, ndiry = 0;   // buffered next direction (latest keypress wins)
-static int tqh = 0, tqt = 0, tqn = 0;
 static int foodx, foody;
 static int score = 0;
 static int best = 0;
 static int speed = 90;             // ms per step (derived from pps below)
-static int pps = 130;              // base speed px/sec; +1 px/sec per 5 food eaten
+static int pps = 100;              // base speed px/sec; +1 px/sec per 5 food eaten
 static unsigned long nextTick = 0;
 static bool running = true;
 static unsigned long now_ms() {
@@ -164,33 +163,19 @@ static void reset_game() {
     snake[i][1] = cy;
   }
   dirx = 1; diry = 0;
-  tqh = tqt = tqn = 0;
+  ndirx = 1; ndiry = 0;
   score = 0;
-  pps = 130;
+  pps = 100;
   update_speed();
   place_food();
   state = PLAYING;
   nextTick = now_ms() + speed;
 }
 
-// Queue a pending direction change; rapid key presses are stored so none are lost.
-static void tq_push(int dx, int dy) {
-  if (tqn >= 4) return;            // queue full: drop the new turn
-  tqx[(tqh + tqn) % 4] = dx;
-  tqy[(tqh + tqn) % 4] = dy;
-  tqn++;
-}
-
 static void step() {
-  // apply the oldest queued turn (no reversing); rapid presses are not lost
+  // apply buffered direction (no reversing); latest keypress wins
-  int tdx = 0, tdy = 0;
+  if (!(ndirx == -dirx && ndiry == -diry) && !(ndirx == 0 && ndiry == 0)) {
-  if (tqn > 0) {
+    dirx = ndirx; diry = ndiry;
-    tdx = tqx[tqt]; tdy = tqy[tqt];
-    tqt = (tqt + 1) % 4;
-    tqn--;
-  }
-  if (!(tdx == -dirx && tdy == -diry) && !(tdx == 0 && tdy == 0)) {
-    dirx = tdx; diry = tdy;
   }
   int hx = snake[snakelen - 1][0] + dirx;
   int hy = snake[snakelen - 1][1] + diry;
@@ -217,7 +202,7 @@ static void step() {
     score += 10;
     if (score > best) best = score;
     int food = score / 10;        // food items eaten so far
-    pps = 130 + food / 5;          // +1 px/sec per 5 food eaten (progressive difficulty)
+    pps = 100 + food / 5;          // +1 px/sec per 5 food eaten (progressive difficulty)
     update_speed();
     place_food();
   }
@@ -288,13 +273,13 @@ static void render() {
 static void handle_key(KeySym ks) {
   switch (ks) {
     case XK_Up: case XK_w: case XK_KP_Up: case XK_2:
-      tq_push(0, -1); break;
+      ndirx = 0; ndiry = -1; break;
     case XK_Down: case XK_s: case XK_KP_Down: case XK_8: case XK_x:
-      tq_push(0, 1); break;
+      ndirx = 0; ndiry = 1; break;
     case XK_Left: case XK_a: case XK_KP_Left: case XK_4:
-      tq_push(-1, 0); break;
+      ndirx = -1; ndiry = 0; break;
     case XK_Right: case XK_d: case XK_KP_Right: case XK_6:
-      tq_push(1, 0); break;
+      ndirx = 1; ndiry = 0; break;
     case XK_5: case XK_Return: case XK_KP_Enter: case XK_space: case XK_p:
       if (state == PLAYING) state = PAUSED;
       else if (state == PAUSED) { state = PLAYING; nextTick = now_ms() + speed; }
@@ -390,12 +375,19 @@ int main() {
   render();
 
   int xfd = ConnectionNumber(dpy);
+  const unsigned long FRAME_MS = 1000 / 60;  // 60 fps rendering
+  unsigned long lastFrame = now_ms();
+
   while (running) {
-    long until = (long)nextTick - (long)now_ms();
+    unsigned long now = now_ms();
+    long until = (long)nextTick - (long)now;
     if (until < 0) until = 0;
+    // Never block select longer than one frame so the screen stays smooth
+    long wait = (until < (long)FRAME_MS) ? until : (long)FRAME_MS;
+
     struct timeval tv;
-    tv.tv_sec = until / 1000;
+    tv.tv_sec = wait / 1000;
-    tv.tv_usec = (until % 1000) * 1000;
+    tv.tv_usec = (wait % 1000) * 1000;
     fd_set fds;
     FD_ZERO(&fds);
     FD_SET(xfd, &fds);
@@ -407,17 +399,22 @@ int main() {
         XNextEvent(dpy, &e);
         handle_event(e);
         if (!running) break;
+        dirty = true;
       }
       if (!running) break;
-      dirty = true;
     }
-    if (running && now_ms() >= nextTick) {
+    now = now_ms();
+    if (running && now >= nextTick) {
       if (state == PLAYING) step();
-      if (state == PLAYING) nextTick = now_ms() + speed;
+      if (state == PLAYING) nextTick = now + speed;
-      else nextTick = now_ms() + 80; // keep loop responsive while paused/over
+      else nextTick = now + 80; // keep loop responsive while paused/over
       dirty = true;
     }
-    if (dirty) render();
+    // Render at 60 fps or whenever state changed
+    if (dirty || now - lastFrame >= FRAME_MS) {
+      render();
+      lastFrame = now;
+    }
   }
 
   XFreeGC(dpy, gc);

src/games/tetris.cpp

@@ -499,12 +499,19 @@ int main() {
   render();
 
   int xfd = ConnectionNumber(dpy);
+  const unsigned long FRAME_MS = 1000 / 60;  // 60 fps rendering
+  unsigned long lastFrame = now_ms();
+
   while (running) {
-    long until = (long)nextTick - (long)now_ms();
+    unsigned long now = now_ms();
+    long until = (long)nextTick - (long)now;
     if (until < 0) until = 0;
+    // Never block select longer than one frame so the screen stays smooth
+    long wait = (until < (long)FRAME_MS) ? until : (long)FRAME_MS;
+
     struct timeval tv;
-    tv.tv_sec = until / 1000;
+    tv.tv_sec = wait / 1000;
-    tv.tv_usec = (until % 1000) * 1000;
+    tv.tv_usec = (wait % 1000) * 1000;
     fd_set fds;
     FD_ZERO(&fds);
     FD_SET(xfd, &fds);
@@ -516,17 +523,22 @@ int main() {
         XNextEvent(dpy, &e);
         handle_event(e);
         if (!running) break;
+        dirty = true;
       }
       if (!running) break;
-      dirty = true;
     }
-    if (running && now_ms() >= nextTick) {
+    now = now_ms();
+    if (running && now >= nextTick) {
       if (state == PLAYING) step();
-      if (state == PLAYING) nextTick = now_ms() + speed;
+      if (state == PLAYING) nextTick = now + speed;
-      else nextTick = now_ms() + 80;
+      else nextTick = now + 80;
       dirty = true;
     }
-    if (dirty) render();
+    // Render at 60 fps or whenever state changed
+    if (dirty || now - lastFrame >= FRAME_MS) {
+      render();
+      lastFrame = now;
+    }
   }
 
   XFreeGC(dpy, gc);