Spacewar (1962) was the first ever computer game, and involves two little spaceships trying to blow each other up. Here is a loving (simplified) re-make, but the visuals have been updated to use the Cairo 2D graphics library. Technically, this means things like anti-aliasing, scalable graphics, alpha blending, and gradient fills. Non-technically, just take a look at (1) the screenshot below, and (2) the close-up below that, demonstrating scalable vector graphics - or SVG. When you get your super-mega-ultra-hi-res monitor in a few years' time, these graphics will just look even smoother, unlike the old games of 5 years back, which just look "blocky" on today's computers.
The game itself is very simple - there are two ships, and they can only accelerate, rotate, and fire. The blue ship is controlled by the W, A, D and (Left) Control keys, and the red ship is controlled by the 8, 4, 6 and Insert keys on the number pad (make sure that NumLock is off).
Run out of energy (the colored bar at the top) and you lose. You lose energy by colliding with the other ship, or with any missiles (including your own). You gain energy (up to a maximum level) by just hanging around, although you recharge faster if you aren't shooting.
The Cairo graphics library is still under development, and so the program is only available in source code form (under the GNU GPL): svgspacewar-0.1.tar.gz.
Version 0.1 requires cairo version 0.4.0, as well as gtkcairo. Once you have these installed, running the program is as simple as:
make ./svgspacewar