Thank you for reviewing this game. I've taken notes during the stream, here's the todo list:
1. Altitude shouldn't be changed so easily. Should add obstacle or cool down.
2. Player can stay in one spot and not getting hit, which should be detected and prevented.
3. Meter counter should reset when player dies.
4. Consider adding color to the sprites as the game progresses.
5. Add boss fights.
6. May add power up items (shield, bombs etc.).
Will fix/implement them one by one.