The Splinters are a splinter group of Project Freelancer dedicated to reviving the project and its research. Led by Agent Nevada, a handful of Freelancers were a part of the Splinters after the downfall of Project Freelancer left the super-soldiers abandoned without purpose. Project Freelancer first sent Wilcox and Meredith (and set up Command) to Blood Gulch years prior to termination, then the Splinters continued this simulation by requesting many more soldiers from the UNSC to be sent to the canyon.
The Splinters lost two members at some point; Oregon and Hawaii, who for some defected. Oregon escaped due to Hawaii's sacrifice, not knowing that she was kept alive and in prison for months. Oregon turned up in Blood Gulch and started a very long recovery process before deciding that he needed to believe Hawaii was still alive. This served as his motivation to gather the simulation troopers up and fight back against the Splinters.
Eventually, the Splinters were slowly chipped away at before finally being wiped out entirely in the explosion of The Child of Necessity, Nevada and the Splinter's central base of operations. Nevada escaped narrowly, only to rather stupidly launch a solo attack on Oregon and Hawaii which ended in a group of simulation troopers killing him and finishing off what was thought to be left of the Splinters.