In short: JusTD is a Tower Defense game with resource- and base management!

The gameplay is simple. You need to expand the map by revealing previously hidden sections as long as there are any, then you need to start the wave! In each wave different amount or type of enemy robots will spawn and will try to reach your main tower, or if they can they will damage your other buildings and turrets. In certain waves boss-level robots will appear with significantly higher stats and if they reach your base, the mission is immediately over! You can build and sell your buildings, but your turrets level up as they attack the enemies, and they become stronger and stronger, so it is better to keep an eye out for keeping them in one piece! You also need to mine minerals and refine them to have resources! The resources can then be used to build or repair buildings and turrets, or to produce ammunition. There are only a limited amount of spaces for your buildings, so you need to choose wisely what and where to build!

The game has a Skirmish and a Campaign mode. In Skirmish you can select the map you want to play on and the day cycle to use. In the Campaign you need to progress from mission to mission with increasing difficulty.

Campaign progression is tied to reaching the minimum wave limit on each map, thus entering the so called Endless wave state. After reaching it, the new waves start automatically when the last enemy is killed, making the gameplay significantly harder! The highest wave reached stats are stored for both the Skirmish and the Campaign maps.

To make the game more challanging, in certain Campaign missions there are Environmental hazards, such as meteor strikes or earthquakes. These are selectable in Skirmish maps.

To help in the late game, you can use the Orbital strike after you killed enough enemies!