Three game modes are available: Duel (online ranked), Spar (online unranked), and ESL Tournament Play (online unranked). Two practice modes vs a bot named Lenore and vs target orbs are also available.
Duel, Spar, and ESL Tournament mode are also available to play directly with friends. (Both will be unranked in this mode.)
Duel mode is the standard mode and consists of a 1v1 3-round death-match. The objective being to kill your opponent by any means necessary, twice. To find players to play duels against, connect to The Unspoken discord and the #looking_for_game channel. Players arrange matches there rather than sitting in queue in VR. Check out the wiki page Tournaments & Events for regular events when players come online at once for duels.
When players battle, the higher ranked player risks losing points if the lower ranked player wins. A lost internet connection counts as a forfeit/loss. When players do not play in too many days, they lose points gradually down to a cap of 600. Coming back in and playing a battle or two can recover their rank.
Spar mode is a 1v1 point collection style single round match that lasts 3 minutes. Points are gained by destroying your opponents orbs whilst also collecting your own. Direct Damage to your opponent will score you points as well but is not as efficient.
ESL Tournament Mode
This mode lets both players change classes and artifacts in between games. Its wins/losses do not affect Duel mode rankings. It does limit the total number of games and then require a re-invite to start again, but can be handy for friends practicing together due to the flexibility of changing artifacts, classes, and locations at whim. Go into the mode first and then invite a specific friend to join you.