You can invite friends to join your lobby through steam by clicking the "Invite Friends" button around the bottom middle of the screen. A maximum of 4 players and 4 spectators can join the lobby before it is full.

One new mechanic in Blaze is the addition of health bars. In the original Lethal League, one-hit knock-outs were the name of the game. In Blaze, those are only possible when the ball is moving at triple-digit speeds. Any hit from the ball just takes a bit off your health otherwise.