I've played them both, and both are good. Besides aesthetics, though, they're not that similar - depends on what kind of game you want more.

X-Com is fully co-op. There is little to no tactical combat, it's all strategy. You'll pick which guys you're sending on missions, but after that it's pretty much just assigning them. It is also app-dependant, so you will need someone to handle manning the smartphone while you play.

Level 7 Omega Protocol is a 1 vs Many game. It's almost all tactics. You pick your characters load-outs, and then try to work your way through the area.

My -personal- preference is Lvl 7, and I say this already owning X-Com. We've played X-Com twice, and it got shelved. I've played Level 7 once at GenCon, and it quickly moved up my list of games I'm interested in - I just have a lot of campaign style games in my backlog already.

X-Com: * Lots of pressure/stress = excitement * Definitely captures X-Com 'feel' for the Director, but NOT the feeling of moving troops around on a map. * Each section is different, so switching feels like a new game * App is absolutely required, but serves primarily as a timer/randomizer * Very difficult to plan ahead (for us at least) * 4-players required, won't work well with less and no spaces for more.

Level 7: * 2 player minimum, but goes up to 6. * One player MUST play as the overlord/alien boss * Overlord's interface is an interesting way to balance the game * Easier to plan ahead, but still difficult to win at times * Lots of tactics - this captures the feel of an individual X-Com map, but you don't have the overarching feel of being the director or running the program. * Difficulty of the game depends a LOT on the skill of the Overlord - unlike some Overlord games, this one really feels like it makes them work for the win. In other games, it becomes more of a GM style role.