The most striking thing about FTL is the simple pleasure of manipulating a starship and it's 2d crew. Forget the roguelike stuff, the difficulty, etc. Just beaming guys around, leveling skills, opening and closing airlocks, recruiting and losing crewmembers and handling weapon configurations/timing makes for such a strong game.
If those mechanics got fleshed out with deeper diplomacy, better graphics, more ships, more freedom and less RNG, we could really have something special. Here's hoping some AAA money gets behind these systems