A friend and I began playing an M2TW retrofit grand campaign about a month ago. We are both enjoying it very much .

We live far apart, and both enjoy "campaign play", so retrofit is ideal. We are each playing a single faction, with the AI handling all the rest.

I wish all the TW games had a way to play PBEM hotseat. If by "playing multiplayer" you mean fighting battles against each other, I'm not even aware how we might do that. We use the retrofit mod to play a "shared campaign", not to fight battles.

I don't have enough experience with retrofit yet to have opinions about favorites units, factions, etc.