A.T.P. Soldats are upgrades of the l33t agents and a product of the Accelerated Training Program along with the A.T.P. Engineers. They differ from engineers in that they wear yellow eyepieces instead of masks and have more specialized fighting skills.
Madness Combat 7.5
During the events of Madness Combat 7.5, Sanford and Deimos attacked a facility manufacturing Soldats.
Two A.T.P. Soldats appeared in an observation room having an online chat session with the Auditor under the screen name "OBSV032." Upon seeing Sanford and Deimos clear a room of agents, they pull our their weapons, a Five-seven and an MP7, and go to stop them. They throw a flashbang and succeed in blinding Deimos, but are quickly killed by Sanford.
At the end of the episode, an A.T.P engineer initiates an upgrade in the advanced Soldat production and releases them on Sanford and Deimos. They fared much better than agents and engineers, but were still killed. After this failure, a critical error occurred in the system and the Soldat production was temporarily halted. When the system attempted to recover itself. Deimos planted a time bomb on the terminal and activated it. With the terminal destroyed, the Soldat production was cancelled for the time being.
Madness Combat 9.5
Among the post-death residents of The Other Place were several ATP Soldats, who had presumably ended up there after being killed earlier in the series. Upon seeing one as part of a group of Agents and Grunts sent to attack him, Hank J. Wimbleton immediately taunted it, pointing to his eye to point out the Soldat's missing one. The soldier took offense to this and tried shooting Hank with a Desert Eagle pistol, but Hank quickly put him down.
Madness: Project Nexus
The A.T.P. Soldats reappear in Madness: Project Nexus, under the name Agent Mk0. They have high a TAC-bar, making them one of the hardest enemies to kill. They are also faster and dodge more often and move faster, making it difficult to engage them in close combat.
Several Soldats appear alongside A.T.P. engineers in the back rooms during Arena Combat Mode. Zombified A.T.P. Soldats appear in Zombie Arena Mode and are the most aggressive and resistant form of zombie in the mode.