Now that the level system is working, the next logical feature would be the first hazard.
At this point in development, most students don’t immediately build fire, saws, spikes, trampolines, checkpoints, menus, sounds, etc. Instead, they usually start by experimenting with one animated trap to learn how animated world objects work.
The fire trap is the most likely candidate because it uses the same sprite-sheet system you’ve already built for the player.