Why do I get instantly killed the moment I open a door?
You are committing the fatal error of opening the door on your final Action Point (AP). When you expend your last AP opening a door in Walk stance, your turn ends immediately. Any enemies standing inside now receive a full uninterrupted turn to fire point-blank shotguns or rifles at your unprotected operative. Always open doors in Sneak stance (which costs 0 AP) or on your very first AP of the turn.
How do I hold off massive Quasimorph hordes during high corruption?
Retreat immediately to the elevator room or a narrow 1-tile corridor. The elevator acts as a 3-sided fortified bunker with a single bottleneck. Close the elevator door using right-click to break line of sight, wait for demons to crowd the doorway, and eliminate them one by one as they step through using auto-shotguns, flamethrowers, or monomolecular blades.
What makes Sneak stance essential even if I am not playing stealthily?
Sneak stance offers two critical mechanical advantages for all playstyles: it allows you to open closed doors for exactly 0 Action Points (free action), and it reduces your weapon scatter cone by 40%. Even for heavy assault builds, toggling Sneak before opening a doorway ensures maximum shotgun pellet concentration and leaves all 3 AP available to attack or retreat.
Can I extinguish fire burning on my operative using drinks in my backpack?
Only if the container is Purified Water. Pouring alcohol, moonshine, vodka, or beer onto a burning floor tile acts as an immediate accelerant, triggering an explosive fireball dealing 60+ thermal damage that will instantly incinerate your operative. If you lack Purified Water, discharge a CO2 fire extinguisher onto the tile or run onto an unburnt floor.