While it doesn't have all of the features I wanted (multiple enemies with different weapon types, for instance), it should at least feel quite complete and self-explanatory.
The enemies get stronger as you go. While it is not how I originally intended, it's the evolution part of the game.
It's a good effort, kinda difficult until you just start clearing out a line of enemies and dodging them. Some things I would have liked to see: faster vertical movement, with less acceleration on it and more direct control, horizontal movement would have been nice for dodging through some of the patterns. It would be neat if the enemies evolved some different abilities or maybe just different movement patterns over the consecutive waves instead of getting stronger and stronger. Some pickups would be cool, or enemy drops to incentivize players to leave their one safe line.
$ sudo apt-get install libsdl-mixer1.2 libsdl-ttf2.0-0
Depending on your system, there may be other libsdl libraries you need too .. follow your nose based on the error.