PiscesMike and I have had a few conversations in the chat room about the theme of this competition. One of the things I found interesting about the last game is how few people stuck exactly on theme. Most people did something with a significant twist, and others didn't even pay any attention to the theme. (I ended up building a clone at the end, because I ran out of time to work on what I was trying to do the first time around.)
Based on that, I think it is probably best to define the theme more loosely than last time.
One thing that came up was to start by picking a game. (And Thrust would be a good choice for this.) The theme would be very loosely based on that game. But then we'd kind of pick apart the game for the "tropes" that it uses, and list some of them out as ingredients or components that you can pick and choose from to follow the theme more loosely. Of course, if you create a clone of the original game we picked, you'd be completely following all parts of the theme, but it would naturally give some more flexibility for people who want to try something a little different.
So for a Thrust themed competition, the tropes might look something like this:
This isn't intended to be a comprehensive list (it would definitely be subject to refinement) and I also have played too heavily on that TV Tropes site with the links and names. It was just easier to use that for the time being than come up with my own. I definitely do not feel like we need to stick with tropes from tvtropes.org.
This kind of approach wouldn't necessarily give you an easier and a harder goal, but it would definitely give you a more focused (create a clone of the original game) and a less focused goal (pick any number of the tropes to use in your game). To be fair, though, it's easier to clone a game than to come up with your own that reuses elements of other games for inspiration. So perhaps it is also an easier/harder goal.
How would that sound to people?