The idea and preparation: some technicalities
I really did not want the theme to be "one room". This is the one that I had no interesting ideas for.
In the end, I'm going to have to resort to a technicality: I'm using my SGE Game Engine, which defines a "room" as something like a level. So I'm going to technically be using only one room (one SGE "room") in the process of developing a game. Because I have a great idea for a game that can fit in that category, but no particularly interesting ideas for games taking place in one literal room. (The best idea I could think of was squishing ants.)
So, this is my idea: a space game. We'll have two teams of ships that shoot lasers. When one team is destroyed, it gets replaced by more ships, and the winning team gets its team only partially replenished. We'll have a sort of meter indicating victories, e.g. it will start at 0, then one team's victories will decrease it and the other team's victories will increase it. When it gets to a certain number, probably either 5 or -5, the respective team wins. Controls will be much like Asteroids, or Spacewar: top-down, with rotation, thrusting, and shooting.
At first I was thinking of making a single-player game that goes on forever, and I wanted to give a nod to Spacewar, so I considered the name "Perpetual Space War", or "PSpaceWar". But that's kind of lame, and I changed the idea anyway. So I decided on "Pacewar". This name makes sense: as you win more and more, you start to have a disadvantage in ship numbers, so you need to destroy the other team faster than your team gets destroyed. This also gives the nod to Spacewar I want to give.
Scouring OpenGameArt.org, I found that I want to use these:
http://opengameart.org/content/sci-fi-space-simple-bullets
http://opengameart.org/content/railjet-long-seamless-loop
http://opengameart.org/content/lasers-and-beams
http://opengameart.org/content/3-spaceships
http://opengameart.org/content/space-ship-construction-kit
Additionally, I'm taking the shoot sound effect from an old scrapped game I did, ITAD S.G..
I also need something for the meter tracking wins. this one might be good. I'll focus more on that later.
Finally, of course, I'm using the SGE Game Engine, specifically the Pygame SGE version 0.12.