Guess if someone is experiencing crashes, it is a big enough change.
H:\tmp\GAME-SDL-PUZZLE-Alizarin_Tetris>git diff
diff --git a/atris.h b/atris.h
index 624e611..c48f46c 100644
--- a/atris.h
+++ b/atris.h
@@ -127,6 +127,9 @@ extern Uint16 FastRandom(Uint16 range);
#define ADJUST_SAME 1
#define ADJUST_DOWN 2
+/* Avoid a buffer overflow */
+#define SPRINTF(buf, fmt, args...) snprintf(buf, sizeof(buf), fmt, ## args)
+
#include "atris.pro"
#endif /* __ATRIS_H */
Updated exe attached.