Welcome to the fan-made site for Gem TD

This is a passion project that spawned from my love for the custom game in Starcraft 2's Arcade. The creator stopped supporting it a few years ago and I felt it deserved something in case anyone wanted easy access to info about the game.

Where to begin


Players attempt to deal the most damage to the final boss. A smaller damage test comes after wave 30 and the final boss comes after wave 50.


Players attempt to deal the most damage to the final wave of 10 bosses. Starting after wave 8, enemies will spawn in squads of 5 units with less HP.


Players attempt to clear all 50 waves in the lowest time. There are no bosses but speed is key.


At the beginning of each wave you are given three options of game type. At this point you may also choose what your mazing rocks look like if you’ve unlocked them with sufficient experience points. After you choose a game type, you must decide what difficulty to play on and at what speed. Here you may also choose what your builder looks like. You unlock builders after beating each difficulty’s specific challenge.


125% Damage


100% Damage


75% Damage


50% Damage


33% Damage


25% Damage

The basics


In Gem TD, the towers you get are completely random. Start by building 5 random gems near the track and pick one gem to keep for the round to begin. The round will not start untill you confirm which gem you want to keep, so take as much time as you need to decide.

Combining Gems

If you build two of the same gems in one round, you can combine them by clicking the “Combine Gems” button on the gem in the position you’d like the final gem to be. Once the gems combine, you will get a gem one quality level higher than the component gems. If you manage to build four of the same gems in the same round, you can combine them to get a gem two quality levels higher.

downgrading gems

You may downgrade any gem you have just built by one level by clicking on the “Downgrade Gem” button. This can be useful when you just can’t seem to get that gem you need to complete a combination.

Gem Chance Levels

At the beginning of the game, every gem you guild will be a Chipped gem. By spending an increasing amount of minerals, you can increase this chance by clicking the “Upgrade Gem Chances” button in your builder’s menu. Eventually you will even be able to build Perfect gems during the build phase!

Lucky chance

Lucky chance gives you a bonus chance to receive a Perfect Gem on the next round. This effect only works once per purchase, and only lasts for one round.

Gem levels







gem abilities

You can hover on the + button in the command card of any gem to find out about its special abilities. The wrenches icon will describe what combination that gem is a part of, and what other gems you need to build to make it.

Gem combinations

Every basic gem can be combined with two or three other specific gems to create a powerful combination gem. When you build all the parts of a combination, whether by chance during the build phase, or by saving each part one at a time during separate waves, they will show a special animation and you can initiate the combine using any of the parts. The final gem will appear in place of the gem that used the “Special Combine” ability.

Plan Accordingly


Mazing is highly advisable to do well in this game. Start by building a spiral of gems around one of the waypoints, and replace the mazing rocks close to the center to get more powerful gems near the center of the maze. Over time you can come up with your own methods of creating an effective maze. The key is to maximize the amount of time your high level combination gems spend attacking the enemies.

air levels

Every 4 levels is an air level. Your maze is useless against air, so make sure you have some high quality Amethysts and other gems near the main path.


In Swarm Mode, on Extreme difficulty and higher, you will start to see captains in later waves. Captains are units with more health and bounty, but they also take 10 lives if they leak through your maze.

Let's Play

Gem TD can only be found inside of Starcraft 2’s arcade. Just filter by tower defense games and we’ll be at the top of the list.

Starcraft 2