System Defender was first released on January 14, 2011 and is playable in the EPF Command Room. It is based on a Tower Defense type game and is used to defend the EPF Mainframe from threats. All EPF Players are able to play this game, but only Members can play all of the game levels which there are seven. The Gameplay in this game is simple where the player will have a system of plugs and a path for Bots to go through where you will have to place cannons to stop them from getting to the EPF Mainframe. There are three different Cannons with different Energy prices that you can earn after each destroyed bot. The Red Cannon is weak in terms of damage, but it is fast and costs 50 energy. A Yellow Cannon has moderate damage output and firing speed and has long range and costs 125 energy points. Finally there is the Purple Cannon that does a lot of damage but fires slowly and does not have long range. Gears are also available to use in order to upgrade you cannons where red cannons can shoot more, yellow cannons have much longer range and more damage, and purple cannons have increased damage, add mini shots and are a bit faster.
In System Defender there are multiple enemies that are found in the game which are Red bots, Yellow bots, and Purple bots. Red Bots attack in large groups, Yellow Bots are fast, and Purple Bots are slow but can take a lot of damage. Boss Bots are also represented in the game where they are larger and a lot harder to destroy. These Boss Bots will also do much more damage to the Mainframe than the regular bots and they are able to drop gears only if you destroy them. Other Enemies which are found in one level include the Ultimate Protobot who is the leader of all of the bots and is able to scan out the layout you placed and will make patterns that will be much harder for you. The Test Bots also make a return where they were supposedly rebuilt by the Ultimate Protobot 10000. Herbert P. Bear is also in this game who is the source and re-builder of the Ultimate Protobot and he also controls the small bots. Klutzy is the main antagonist in one level but it is because he mistakenly believes that Herbert's Computer is an Arcade game and attacks the EPF. You are able to play System Defender and add 14 new Stamps to you Stamp book collection where it was originally going to have 16 but two got removed which were the Strategic 318 Stamp and the Energy 9999 Stamp. One thing to notice that is very interesting about this game is there is a Card Jitsu Card that shows all of the enemy bots, but there is one that is unseen and will probably never make it into the game.