game modifications
Player properties -- Players start out immortal,
meaning that they cannot "die" while exploring the world.
Furthermore, continuous sprinting is enabled, which allows the player
to walk around faster.
Puzzle HUD -- When the player starts out,
the puzzle HUD is the only HUD element displayed.
Puzzle setter -- Allows puzzle parts to be displayed on the puzzle HUD.
Weapon enabler -- Allows weapons to be enabled/disabled for the player.
Enabling the weapons also enables damage, and swithes from
the puzzle HUD to the default Half-Life 2 HUD,
which displays weapon and damage information along with a crosshair.
