I find that a simple RPG like FF1 or something similar to the RPG maker group is a good way to test your skills and have a bit of fun.
You can practice Dialog, Math/Battle Systems, Maze/Quiz Puzzles, and a good amount of small mini game type events.
Most of them are easy, you can write simple RPGs by hand in a few languages once you get the movement interface down, mostly just need to know variables, if/than, switches, and timing.
Good luck!