Crusader is divided into missions, each with their own locations and objectives. Settings vary from factories to military bases to offices to space stations, and contain a variety of enemy soldiers and servomechs, traps, puzzles and non-combatants (who can be killed with no penalty and their bodies can be looted for credits). All locations have alarm systems which are triggered by walking into view of security cameras or destroying a secured door, and can be deactivated by using an alarm box. So long as the alarm is active, either a new enemy soldier will teleport into the area every few seconds or a confined servomech will be released, depending on where the player is. In addition, the player cannot use keycard slots or door switches while an alarm is active. In the PC version, the Silencer can carry no more than five firearms at once. The game featured an unprecedented level of setting interaction. Most of the environment can be destroyed by weapons fire and some traps or defenses can be manipulated for use against the enemy. The geography of the setting encourages the use of tactics and combinations of moves in order to hit the targets effectively with the minimum possible loss of resources. No Regret added a handful of new maneuvers to the original game, including the ability to dive forward, and to sidestep while crouching. Weapons, ammunition, credits (money), healing facilities, and other equipment are scattered through the levels, allowing the player to upgrade their arsenal.