Scratch

You could make a platormer, but if that's too generic, try an RPG.

RPGs take lots of art skill, so if that's not your strong point, I suggest a platformer.

You'll need to pick the character's species and the setting of the game. I usually use online random generators, but it's better to just think of any animal. For an example, lets take a tiger.

RPGs are little virtual worlds that you must achieve something in. Take Wes64's Spectrum as an example.

You can make it a platformer, too; A good example of this is UltraJordan's Blob series.

The setting is simple; Choose the time, place, and goal. Future, present, or past; forest, sea, or city; destroy, protect, or collect. It's all up to you.

So, you can make a platformer in which you play a tiger, and you must collect all of the Emperor's Rubies before the evil Bruce Lee steals them. This takes place during the Ming Dynasty in China.

Hope this helps!