Fun fact! Once you reach get far enough (after beating the game) you run into "features" concerning number representation, the lvl 15 wonder costed -1.8B and upgrading to lvl 50 was essentially free... Then you get ~2k research points in one turn and after upgrading selection to lvl 500 the food gain reads "+null" :D
Just getting the ballon working is really easy, but it is even possible to get 20/20 in-game-achievements? Killing 1000 enimies in less than 4 days seems undoable.