CheckSix Gaming's debut Halo roster was formed in the offseason between the 2004 and 2005 seasons. It consisted of Matt "Zyos" Leto, "Sergio", Tom "Tsquared" Taylor and Jeremy "Tupac" Hodges. Zyos, Tupac and Tsquared were all successful Halo: CE players while Sergio was a relatively new face on the scene. CheckSix was the first fully sponsored Halo team. Their first event together was MLG Washington, D.C. 2005, where they placed 2nd, falling to Shoot to Kill in the finals. Following D.C., Tsquared and Tupac left CheckSix, and the remaining members recruited Nick "KillerN" Urso and Alex "Toxin" Varouhas. They once again placed 2nd at MLG San Francisco 2005, again losing to StK. Toxin left the team after the event, facilitating the return of Tupac. At MLG Houston 2005, the new roster managed to defeat StK 3-2 in the WB finals, but StK came back to defeat them 6-3 in the Grand Finals. The Check Six roster returned for one more event at MLG Orlando 2005, where they placed an uncharacteristic 5-6th, being eliminated by Str8 Rippin.
CheckSix returned to Halo for the start of the 2006 season, again sponsoring Zyos' team. This time, the former XiT Woundz roster consisted of Zyos, KillerN, Corey "Bonfire" Howard and Tyler "Itwasluck" Howard. Despite a respectable 4th place finish, CheckSix did not continue to sponsor the team, and they returned to using the XiT Woundz name at following events.