Update: It is finished!
Here is the relevant post.
Transdimensional Hellspider is a space shooting game thing that I can best describe as Spacewar! vs Warning Forever. It's like Spacewar! in that there is inertia and thrust (and the enemy has a basic physics model hacked together out of dim recollections of year 12 physics), and like WF in that, well, WF really owns the idea of a boss which keeps on evolving based on how you kill it. It's written in C and uses Allegro.
Here are a couple of screenshots:
As you can probably see, the viewpoint is fixed forwards and the world rotates around you, which was a bit hard to get right but seems to work well despite requiring thousands of arctangent operations each frame.
The game is fairly close to done. The gameplay is there, although it needs balancing and sound. I hate doing sound, it is something I always leave for last.
Further updates as progress continues!