Crystal Maze TD

You don't place towers along a road here. You build the road. Every round you set down five random gems anywhere on an open cavern floor, keep the one you like best, and the other four turn to stone. Gems and stones are both walls, so each round the horde's path gets longer and twistier, and it always has to pass two rune checkpoints on its way from the entrance to the exit. You can never seal the path completely; the game refuses any gem that would.

Fusing crystals is where the strategy lives. Two of this round's gems that combine can be fused instead of keeping just one, and any two tier-1 towers already on the board can be fused later. The pair decides the result: two rubies make an area-of-effect Inferno, two sapphires a freezing Frost Nova, and cross-type pairs like ruby with sapphire, emerald with amethyst or topaz with onyx each produce their own crystal. Fuse two of those tier-2 results and you reach tier 3.

What you build has to answer what is walking at you. Damage comes in eight types and every enemy resists something: the Golem shrugs off half of all physical damage, the Specter halves magic and flies straight over your maze, the Ironclad halves both fire and physical, and the Crystal Titan resists everything except pure damage. Spores split in two when killed. Gold from kills pays for tower upgrades.

Thirty waves, one cavern, and every player's maze looks different.