Press ~ during game play to activate the console window, then activate the following cheats by entering the corresponding codes:
CHEAT FUNCTION - CHEAT CODE Refill current weapon's ammunition - ammo Toggle attacking your allies except for Dexter and important characters - set player.friendlyfire <0 or 1> Set gravity; -32.15 is default, larger values allow higher jumps - set phys.gravity.y Set walk speed; 18 is default, higher values increase speed - set player.speed More upgrade points for guns - guns.points Toggle God mode - set god <0 or 1> Set melee range; set to 10000 for unlimited - set melee.reach Toggle invisible to enemies - set player.ghost <0 or 1> Set water level; 0 is default - flood Removes NPCs from map - clear-npcs Set gunslots to carry more guns - set player.gunslots Toggle turrets from overheating - set gun.heat.rate <0 or 1> Spawn of blue aura characters - specialize Set friction - set player.frictionHL Toggle smoke and effects when NPCs fire guns - set npc.gunparticles <0 or 1> Toggle NPC muzzle flash - set npc.gunlights <0 or 1>
Go directly opposite all the characters and use the wooden door in the last scene. You will be able to enter after all the action is over. The bonus mission involves protecting the development team. You can see hidden text during the bonus levels by looking at the subtitles.