How does it compare to the earth defense force games?Not nearly as arcadey in feeling as edf but there can be large swarms of enemies that you fight but it's more objective based then edf.
Can you play it single player?It's somewhat similar to mass effect 3 multiplayer but it's not a closed off map but you do approach the game in a somewhat similar manner of it being position based and knowing when to get out of situations and kite enemies.
How does it compare to Mass Effect 3 MP? Probably one of the only MP modes I've ever enjoyed.