I already own proteus and awesomenauts any single games?
i'm thinking ace of spades
Ace of Spades is a money hog. Just get the old version, it's still around and played as far as I know. Nevermind, Jagex took the original down too. forget Jagex.
I would recommend you to wait for Summer Sales, even if you do have to wait 1-2 months eventually, you could rack up more money and then get epic sales.