Onet Number is a connect-style tile-matching game that shares similarities with Mahjong games. The player must clear playfields of colorful tiles marked with white numbers in matching pairs. They must also attempt to earn a high score in the upper-center area.
The player can only remove tiles that have identical colors and numbers. The game uses blue energy lines to connect selected pieces. The player can't remove any matching tiles that require more than three energy lines to connect or the equivalent of two right angles of lines. As a result, they can only connect side-by-side and stacked adjacent tiles and any tiles across gaps with a distance that doesn't break the rule.
When the player selects a tile, pulsing white targeting brackets appear around the number. The number also becomes teal. The connecting line appears as a single straight bar or multiple lines with angles, and then the tiles disappear from the screen. On some levels, the remaining tiles slide into any gaps that form from the top, left, right or bottom.
Onet Number offers two helpful tools in the lower-right corner. The player can use a button marked with double arrows to shuffle all remaining tiles into new positions that reveal matches that meet the connecting lines requirements. Additionally, they can use a button marked with a magnifying glass to reveal two matching tiles. The tool turns the tiles green.
After the player wins, they unlock the next level. They sometimes also receive additional free access to one or both helpful tools. If they fail, they're bounced back to the first level and their score resets.
