Founder Units are special, limited edition Units given to Founders within Mech Mice Tactics. They are obtained by users who pre-ordered the game for $14.99 (originally $19.99 before being "discounted" to allow players to think they were purchasing it for a cheaper price) during the Beta Test. They are now free to use for all players in Mech Mice Tactics after an update, outraging many Founders.
- All Founder Units were given yellow and black caution fatigue coloring schemes.
- All of the Founder Units have Paint splattered in various places.
- All the Founder Units names are Greek alphabet characters.
- Originally during the Beta Test, to receive the Founder Units, it depended on how many Founders bought the Founder's Package. (For example, Gamma needed 250 Founders and Omega needed 10,000 Founders). But, they later changed it by how many bugs were destroyed. However, by September 25, 2013, only 321,000 bugs were destroyed, and only Gamma and Turner were unlocked. (for an example, Pi needed 400,000 bugs destroyed and Omega needed 1,000,000). On September 25, 2013, the Mech Mice Blog announced that they decided to give all of the Founder Units to everyone who bought a Founder's Package after the official release of Mech Mice.
- The Founder Units were available during the Beta Test from July 9, 2013 to October 7, 2013, which was almost 3 months.
- Beta was the only free Founder Unit that could be earned without purchasing the Founder Package.
- Store Units are commonly mistaken as Founder Units, though they were unlocked as part of the Founder Package.