Main island

The experience description says you can beat up to 350 stages. A Conqueror badge is awarded for completing stage 350. Earlier badges mark stages 1, 10, 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, and 325.

The experience description says rebirth earns overpowered mythic items. Badges exist for the first rebirth and for 10, 25, 50, and 100 rebirths. The coin, gem, or stage requirement is not published, so use the requirement shown on the rebirth control in game.

The current description still says a new code arrives at 15k likes, and the only code strings it names are 10KLIKES for coins and WINTER22 for gems. It does not name a third code for that milestone.

The experience description says to turn off bullets in settings or lower your graphics quality.

Yes. The Roblox group named Tower Defense: Mythic is owned by MuPower and its description links this experience. A run-speed bonus is not stated in that group description.