Map Veto Format

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 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.
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. If a knife round is enabled, sides on the Decider are settled by the knife round rather than a Side pick.

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.

Best of 1, 7-map pool

Ban → Ban → Ban → Ban → Ban → 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

Ban → Ban → Pick → Side → Pick → 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

Ban → Ban → Pick → Side → Pick → Side → Ban → Ban

Once the two picks needed for a best-of-3 are in, the remaining steps are all bans — the Decider is whatever survives.

Best of 5, 7-map pool

Ban → Ban → Pick → Side → Pick → Side → Pick → Side → Pick → Side

Four maps are picked (with side responses), and the seventh map is the Decider — five maps total.