Skill level

Skill level determines the overall difficulty of a game - how many monsters and powerups are out there, how much ammo various items give, etc. There are 5 of them:
 * 1) Determines the number & type of things in maps. This means that skill levels of the same class have the same number and same types of monsters and items.
 * 2) Ammo powerups give twice as much ammunition as they do on other skill levels.
 * 3) All damage the player(s) take is halved.
 * 4) Monsters respawn 8 seconds after being killed. This modifier can be used with any skill level using the -respawn command line parameter.
 * 5) All monsters attack more often, Demons move & attack 2 × faster, Imp fireballs are 50% faster and Cacodemon, Hell Knight & Baron of Hell fireballs 33% faster. This modifier can be used with any skill level using the -fast command line parameter.