If we are discussing multi-homeworld and multiplayer vs single player balance, honestly I think at high levels, single player tends to be quite a bit harder than either of these two cases. I think one of the main reason is with waves, since (iirc at least) at 8,9 and 10 the ai's each get an extra wave, and 4 waves instead of 1 is a much larger difference than 11 waves instead of 8. Any chance of reworking the wave mechanic to be at least a little nastier at higher player counts (perhaps something like 1 extra wave per 2 additional starting waves, so with 3 players it would go 3,5,7,9)? I seem to recall hearing something about how ai reinforcements also scale at about 1/3rd of a player per additional player, any chance of pushing this up to 1/2 as well?