While the SP playthrough is more or less ready, there have been some COOP server runs conducted that have shown us that the maps require a little extra care. While vanilla COOP is mostly accounted for there are a few events that potentially caused progression issues during the usual hijinks that comes along with multiple players monkeying around.
In addition, tests with the RLcoopE community have revealed some loopholes in the level design that needed attention due to enhancements in the player abilities (being able to squeeze through certain gaps, ect).
