If you need an idea for a game, try this random game mechanic generator:

A full list is at the bottom of this page. I wanted to get fairly low level with these game mechanics, so I don't include things such as "first person shooter" or "puzzles" (since those are, in my opinion, more correctly called genres).

Just to prove to myself that this generator isn't worthless, I decided to make some small Python/Pygame games based off of it. These games are fairly rough since I wanted to rapidly produce them as proof-of-concepts. The mechanics that got selected were:

Hidden Image / Where's Waldo?, Switch Modes, Avoiding Unkillable Objects which resulted in "Flag Capture" - A game where you have a specific target flag to pick up out of a sea of red or blue flags. While in blue mode the red flags will hurt you and while in red mode the blue flags will hurt you. You must move your character close enough to the target flag to click on it with the mouse and pick it up.

Bouncing Objects, Bullet Hell, Teleports which resulted in "Incoming!" - A game where you must survive shots being fired at you. Complicating matters is that there are several teleports that the bullets could enter, making it tricky to figure out where they'll be coming from.

Download the games. (Requires Python & Pygame installed to run.)

The full list of mechanics and their descriptions are below: