The 2DStub is close to being a game, though it's primarily meant to be a piece of code for the developer to improve.
In the 2DStub game, besides the player, there are two kinds of critters: rivals and props. The rivals have bitmap sprites, and the props have polygonal sprites.
The rivals shoot bullets at the player. They run away from the player bullets so fast that your only hope of killing them is to chase them down.
Chasing them down is made harder by the fact that they wrap around the world, but your player doesn't.
The props run away from the bullets of the rivals and from the player bullets. If the player runs over a prop, the player's health is improved by one point. The props are like health-packs.
Unlike the Spacewar game, the player needs to move around a lot to do well in 2DStub. Trying to sit in the middle of the screen and shoot is a losing strategy, as the rivals are so evasive and since the props need to be chased down.
The player's default controller is the Scooter Controls.
The game world is larger than a single screen, and we start with a zoomed-in view.