Koboldly Go! is a one page rpg (or two pages if you don't print one on the back of the other) about kobolds in space.
It is delightfully crunchy, but also easy to play and it packs a ton of design into its short page-space.
It's got a system for building a ship from a deck of cards, it's got cool abilities and custom classes (including a redshirt whose mechanic is that they die frequently but always come back,) it's got an FTL-style room-powering system, and there's flavorful stats and multiple phases to combat that allow you to plan, give orders, and act each round.
It may not be a good first game for folks who haven't played trpgs before, as its rules take a little interpretation in a few places, but it has an extremely fun structure, and if you're familiar with 5e and want to see what kinds of cool things other game systems can do with crunch, buy this.
Alternately, if you want to play Star Trek but as a bunch of hectic screaming lizards, you should also buy a copy.
Minor Issues:
-How do you determine reactor size?
-Under Make It Go!, attacks are implied to use d20s. Likewise as part of the captain's ability. However under Beam Me Down!, everything is said to use d6 pools.