GemTD rules
Goal
Outlast your rivals. Everyone has their own 17×17 board and their own 100 HP castle, and the waves run in parallel and are the same for all. A player is out when the castle drops to zero, and the last one standing wins. If everyone survives the final wave, the win goes to the highest remaining castle HP; equal HP is a draw.
Building
Each build round you place exactly five stones. Placing is free — the limit of five is the price. The colour is one of eight with equal odds, and the quality depends on your level.
A stone cannot go on an occupied cell, on any of the seven path points, or right next to a live creep. A placement that leaves any of the six route segments impassable is rejected outright — walling the creeps in is impossible.
Choosing from the five
After the fifth stone you decide what to keep. You can take a stone as it is; two identical stones in the five give +1 quality and four identical ones also allow +2. For 200 gold the quality can be dropped by a random number of steps, and if the five contain the components of a recipe you can assemble a combo tower or a plate right away.
The four stones you did not keep turn into walls and stay in the maze forever: the only way to free a cell again is to demolish the wall.
Gems
- Diamond is raw damage, aquamarine is attack speed, topaz splits across four targets, ruby cleaves.
- Sapphire slows, amethyst cuts armour, emerald poisons, opal gives neighbours an attack-speed aura.
- Qualities run from chipped to huge, and huge never drops from a placement — only merges produce it.
Waves
A wave is ten creeps spawning once a second; a boss wave brings exactly one unit. Fifteen of the fifty waves fly: they ignore the maze entirely and travel in a straight line between the same points.
The build phase has no timer — the wave starts as soon as the first player catches up to the current number. Whoever falls behind gets extra build rounds, and a debt of two rounds or more halves their gold.
Tips
- Make the first loops long rather than dense: you will still need room for towers later on.
- The four walls per round are maze material, not waste — decide where they actually help.
- Flying waves go straight, so maze length does nothing against them: keep damage close to the castle.
- Do not sit on a build round: a debt of two rounds halves your gold and makes catching up harder still.