How multiplayer works, from the first Sludge row to the last blob standing.
Versus play changes the point of clearing lines. In solo, a clear buys you space. Online, it also becomes Sludge in someone else's Well, so the same board that keeps you alive is your weapon, and the best defence in the game is a bigger clear than the one coming at you.
There are two formats, duels and rumbles, and each comes in three flavours: classic, Mayhem and Loadout. Every one of those tracks its own rating, so being good at classic duels says nothing about your Loadout rank.
A duel is a single game against one opponent (not a best-of series. You win when their Well overflows. What you clear becomes Sludge in their Well) from a Double upward, since a Single sends nothing: what they clear arrives at you the same way, and either of you can cancel incoming Sludge by clearing during its pending window.
No duel can stall forever. Sudden death begins at 3:00: from then on both Wells take a rising Sludge row every 10s, and the level floor climbs one step every 5s until it reaches level 15. The floor only ever raises your speed: if your own clears already put you higher, you keep the higher level. It is a gradual acceleration rather than a jump to top speed, so the endgame is still played rather than survived.
A rumble seats 5 players. You see your own Well full size with the rest as live miniatures beside it, and you are eliminated when you overflow. Your finishing position, where first place is the last player standing, is what your rating settles against, and it settles the moment you are knocked out rather than when the room finishes, so leaving early does not delay the result.
Rumbles end on a clock too. The finale starts at 5:00: from then on every surviving Well takes a rising Sludge row every 5s until only one player is left.
With more than one opponent available, you choose where your attacks land. 5 targeting options are available, switchable mid-game:
Targeting also steers your offensive items, not just your Sludge. The other four strategies sit on the number keys 1–4, so you can switch approach without leaving the keyboard.
Eliminating a player transfers their badges to you, plus one for the kill. Each badge you hold adds 25% to the Sludge you send (items are not boosted) so a double eliminator hits meaningfully harder than a player who has taken nobody out. The bonus rounds down, which means one badge adds nothing to a send of only a row or two; it starts paying on the big clears. A badge only ever comes from a kill: if the eliminated player topped out on their own, or the player who last hit them is already out, those badges simply disappear. A player who is eliminated drops all of theirs to whoever finished them, so the biggest threat keeps moving, which is what Leader targeting is for.
Every queue game is rated; there is no separate casual queue. Ratings are tracked per format and shown as titles; see Ranks & Rating.
If nobody suitable joins within a short wait, the empty seats are filled with bots so you are not left staring at a queue, and in a rumble, a human who joins later takes a bot's seat. Private lobbies work the other way round: you create one, share the code it gives you, and anyone with that code joins your room. Private games are always unrated, and the host decides whether bots may fill the remaining seats and at which difficulty.
Three habits separate versus from solo. First, watch the pending count beside your Well and clear to cancel rather than to score: a clear that exactly matches what is incoming means neither of you gains anything, and that is a win when you are behind. Second, every Sludge volley arrives with one shared gap column, so dig by clearing several rows at once through that column instead of nibbling the top. Third, your handling settings are locked in when the match starts and sent with it, so both players are on settings that cannot change mid-game, tune them before you queue, not after a loss.