There is no multiplayer or co-op. We are a small indie team and unfortunately didn't have the resources to commit to a co-op mode.
I'm not sure if gifts include the Steam key. Bundles definitely don't, but maybe the person who purchased the game for you has the ability to request a Steam key on the purchase page. If you are not able to do that we could DM you a left over key from our Itch redeem list.