MergeTD by DJMX is a tower defense game available on Windows. It is a strategy game that requires players to indulge in mental calculations to defend their territory against monsters.

MergeTD has a sandbox-style free play that allows players to create endless possibilities through the layout of enemy interception. Players can also compete globally on the game's leaderboards to make progress.

The game has strategic compositing upgrades that require players to compose more than three connected towers of the same kind to create advanced towers. Additionally, if more than three towers are upgraded, they can get a stronger attack reward, referred to as "super attack Tower."

The game features various towers and enemies. Players can use items like bombs to deal direct damage to towers and enemies. The towers range from the Yellow Tower, which has single-point attack and high-speed output damage to enemies, to the Purple Tower, which has penetrating sustained damage. The enemies range from normal monsters, which have balanced health and speed, to bosses, which have terrible health and are new player killers.

Overall, MergeTD is an exciting game that requires players to build up their firepower to defend their territory against monsters.