Dr.Sum is a brain teaser game by KITERETSU.INC that challenges players with number puzzles. The game's main concept revolves around using math addition to rearrange panels in the correct order. With various gimmick panels along the way, players can exercise their brains while having fun. Dr.Sum offers different levels of difficulty including Normal, Time Attack, and Endless, providing a variety of challenges for players to enjoy.

Players can test their skills by clearing all 50 levels in the Normal Level mode, or challenge themselves to solve puzzles within a target time in the Time Attack Level. For those seeking an endless challenge, the Endless Level offers a level with no predetermined end, keeping players engaged in the game.