Done! Now obstacles and pickups show math equations (addition, subtraction, multiplication, division), and hitting an obstacle triggers game over.

**Next Ideas:**
1. **Score System** - Track total enemies destroyed and display a final score with letter grades (S, A, B, C)
2. **Difficulty Levels** - Add Easy/Medium/Hard modes with different equation complexity and spawn rates

**Ready to level up your game? Pick one and let's build it!**