Edge of Space" is a mini Sci-Fi RPG. When I say, "mini" I mean it. It was initially designed to fit the PocketMod format, which is to say it prints on a single page and folds into a little booklet giving you 8 tiny printed pages.
When you purchase the PDF you actually get two versions of it, one in the PocketMod format and one in standard layout suitable for on-screen or even eReader use (my Sony e-book reader handled the PDF perfectly well).
So what's in here, you ask?
You get the barest hint that Aliens have attacked Earth and a space force is required to battle them. Next it's straight into character creation. This has just a hint of the Traveller feel in that you pick a career and roll for skills (but you'll be glad to hear, there is no death during chargen).
After that you "join" your characters together using "strings" which can be used during play to increase your chance of achieving things. I found this quite innovative, I've not seen this idea before. It builds relationships directly into the system and allows you to use them mechanically during play.
Beyond CharGen are a few more rules on how to achieve things, teamwork, initiative, advancement, all of the usual sort of things.
The real strength of this game is its portability, and I don't only refer to the fact you can print it and slip it into a top pocket, but also of the fact that it's rules-light approach will fit in almost any Sci-Fi setting you want.
Imagine if you will, that you do have this game in your top pocket, someone mentions a cool film (Aliens/Battle for L.A./Predator) and BLAM(!) you have the game there you pull it out of your top pocket. In ten minutes you'll have characters and a system everyone will get their heads around in no time at all.
This game can be purchased for 99c at RPGNow.com