Map Veto

5Stack uses a deterministic, tournament-standard ban/pick algorithm to turn a map pool into a playable series. The same rules apply to every match, so the sequence of bans and picks is fully predictable and reproducible from two inputs alone:

• the map pool (how many maps are eligible), and
• the best-of (how many maps the series is played to).

The order follows Valve's Major Supplemental Rulebook, generalised so it holds for any pool size and any best-of, not just the 7-map best-of-1 and best-of-3 the rulebook spells out. Where 5Stack departs from it, it says so below.

Players make the veto on the veto board, which can also show veto scouting: each side's record on every map and the other side's usual bans and picks.

The rules

1. The veto runs for pool − 1 steps. The single map that is never banned or picked becomes the Decider.
2. The building block is a repeating unit of Ban, Ban, Pick, Pick, with the two teams alternating turns. Every completed pair of picks reverses who leads, so the picks snake — see Turn order.
3. As soon as the series has enough picked maps to satisfy the best-of, every remaining step is a Ban. There is no point picking maps that can't be played.
4. When few enough maps remain that bans would dip below what's needed, the remaining steps collapse to Picks.
5. After every Pick, a Side step is inserted so a starting side (CT / T) is chosen for that map.
6. The leftover map is the Decider, and it is never a Side pick — the knife round settles sides on it.
7. Any extra bans a larger pool requires land after the picks and before the Decider. The Decider is always the final step, whatever the pool size.

Turn order

Teams alternate turns and Team A — the first lineup on the match — opens the veto.

Every completed pair of picks reverses who leads. The picks snake:

Pick 1: A    Pick 2: B    Pick 3: B    Pick 4: A

Without the reverse, the team that opens the veto would take every odd pick and the last ban before the Decider, and that last ban is effectively the choice of what the Decider is. The reverse hands the second half of each phase to the other team.

This is the rulebook's own order. Its best-of-3 process has Team A pick map 1 and Team B pick map 2, and then — after the picks — "Team B removes one map, Team A removes one map": B leads the second ban phase, not A.

The starting side on a picked map is never chosen by the team that picked it — it always falls to the opponent. The Decider is never a side pick: nobody picked that map, so the knife round decides who starts where.

Where 5Stack differs from the rulebook

Valve's Major Supplemental Rulebook covers two cases only — a best-of-1 and a best-of-3, both on a 7-map pool. 5Stack follows it on both, with these deliberate exceptions:

Rulebook	5Stack
The Decider's starting side is chosen by a team (Bo3 step 10, Bo1 step 5)	Nobody picks a side on the Decider — the knife round settles it
Best-of-1 bans are split 2 / 3 / 1 between the teams	Bans alternate, so the pattern is defined for any pool size, not just seven
No best-of-5 format	The same rules extend to it: four picks, snaking A, B, B, A

When there is nothing to veto

If the map pool holds exactly as many maps as the best-of, every map in the pool is going to be played and there is no decision to make. The veto is skipped entirely and the maps are assigned straight from the pool with alternating starting sides — a best-of-3 with a 3-map pool goes directly to the first map.

Rush matches never run a map veto: they are always a single map.

Pick timer

Each step has a time limit, set per match by Veto Pick Timer. New matches start with the instance default from Settings → Application → Matchmaking (60 seconds unless an admin changes it). Set it to 0 to remove the limit and let the veto wait indefinitely.

If a team runs out of time, the step is made for them:

• a Ban or Pick takes a random map from those still available
• a Side takes CT or T at random

Auto-taken steps are marked Auto, so a completed veto shows which steps a team made and which ran out of time. The timer restarts on every step, including auto-taken ones, so a veto always finishes.

When it's a player's turn and they're on another page, a Map Veto (or Region Veto) toast tells them so, with a button straight back to the match. See Matches.

The veto board

Map and region vetoes run on one board, on the match page and in a draft room. It keeps the same height from the first step to the last, so the page doesn't jump between turns.

• A status line names whose turn it is (Your turn when it's yours) and the step, such as Ban a map, Pick a map, or Pick your starting side on Mirage, with the step count and the time left.
• Under it, the order of play lays out every step of the veto, made or still to come, with the team each belongs to. On a phone it becomes one row per team.
• Each map shows what happened to it: who banned it, or its number in the series (Map 2, Decider · Map 3) and who picked it.
• On your turn, click a map, then confirm with the button that names it, such as Ban Mirage. From the keyboard, the arrow keys browse, Enter chooses, and Esc clears.
• A side step splits the picked map into Start CT (Defend first) and Start T (Attack first).
• In a region veto, each region shows your ping to it.

When the match still needs its server started, the board stays up after the last step, reading Waiting for a server, Server booting, then Server ready with the first map and, for players, the side they start on. Then the maps move into the match page's map cards, and the order of play moves into the match header, under Veto, for the rest of the match. In a draft room the board stays on Match starting until the room hands over to the match page.

Veto scouting

During a map veto the board can show what each side has done before, so a ban or pick is made knowing the other side's record and habits. It's on by default for Competitive, Wingman, and Duel matches, wherever they come from: matchmaking, a draft room, a tournament, or Schedule Match. An admin can switch it off per mode, see Veto scouting. Rush has no veto, so it has no scouting.

The history depends on who is playing:

Side	Map record	Bans and picks
A team	The team's results in its recent vetoed matches	The team's recent vetoes
A pickup	Its players' own results on each map, added together	The captain's past vetoes as captain

A side is a team when it plays as one of the instance's saved teams; any other side is a pickup. The veto being made is never part of the history.

What the board adds:

• Edge: each open map, and each map that will be played, shows the gap in win rate between the sides. As a player it reads from your side: +12 when your win rate there is 12 points higher than theirs, −12 when it's lower. A spectator sees the stronger side's crest beside the number. Win rates within 5 points read +0, and a map where either side has fewer than 3 games reads —.
• Win rate on map: on your turn, the map you point at or select opens with each side's wins, losses, and win rate there (You for your own side).
• Usually bans / Usually picks: a map the other side banned in at least half of its vetoes, or picked in at least 40% of them. Hover for the count, such as Team A ban it in 6 of 9 vetoes.
• Likely ban / Likely pick: while the other side is on the clock, the open map it has banned (or picked) most often, once that's at least 30% of its vetoes.

Players see the other side's habits, and spectators see both sides'. A habit needs at least 3 past vetoes behind it. If the history can't be loaded, the veto runs the same without it.

Veto scouting reads the same recorded vetoes as a team page's veto tendencies and veto simulator, but on the board itself, during the veto, and for pickups as well as teams.

Step types

Type	Meaning
Ban	The acting team removes a map from the pool.
Pick	The acting team selects a map to be played in the series.
Side	A starting side (CT / T) is chosen for the just-picked map.
Decider	The final unbanned, unpicked map, assigned automatically.

Examples

The pool size below is the number of maps eligible for veto. The final, unlisted map in each row is the Decider. A and B are the two teams, A opening.

Best of 1, 7-map pool

A Ban → B Ban → A Ban → B Ban → A Ban → B Ban → (Decider)

Six bans leave a single map. With a knife round enabled, sides on that map are decided by the knife.

Best of 3, 5-map pool

A Ban → B Ban → A Pick → B Side → B Pick → A Side → (Decider)

Each team bans one map, each team picks one map (and the opponent's side response follows each pick), and the last map standing is the Decider.

Best of 3, 7-map pool

A Ban → B Ban → A Pick → B Side → B Pick → A Side → B Ban → A Ban

Once the two picks needed for a best-of-3 are in, the remaining steps are all bans the Decider is whatever survives. The pick pair reversed the lead, so B opens the second ban phase and A has the last ban.

Best of 5, 7-map pool

A Ban → B Ban → A Pick → B Side → B Pick → A Side → B Pick → A Side → A Pick → B Side

Four maps are picked (with side responses), and the seventh map is the Decider, five maps total. The picks snake — A, B, B, A — so both teams pick twice and neither gets both of the middle maps.