With all game/software/product that you want to sell you have to have an market for the the product and fortunately the Outerra product sells it self because it is something that has not been created yet, but...
If you want to create a game that sells very easily i would suggest you guys create a city building game (like simcity 4) on top of your engine there has not been a proper city building game for YEARS !!! and the biggest fall back to all city building games is the map size, and fortunately for Outerra that is not a problem.
There is still allot of people that are still playing the old simcity 4 that was released in September 22, 2003 as it was the last descend one but is very old. there where other releases but didn't supplied what the community wanted.
Cities XL : Original Company went bankrupt and poor performance was done for the game and lost allot of players.
Simcity (2013): Nice simulations and mechanics but far to small maps and players got frustrated as they want to build massive cities.
references of communities:
http://www.simtropolis.com/http://www.sc4ever.com/http://www.sc4devotion.com/forums/http://www.simcityplaza.de/Developing a city building game will also be a great test for your engine as it wont demand as much graphics and detail as a First Person Shooter and will be a great benchmark for future development wit other games.
in short what the comunity want is... and i am certain you can do this
