Quake 2

Level Skip:

Okay, when in game, bring up the console by pressing ~. Then, type map . The codes in which needed to skip are listed here:

Outer Base - base1.bsp
Installation - base2.bsp
Comm Center - base3.bsp
Lost Station - train.bsp
Ammo Depot - bunk1.bsp
Supply Station - ware1.bsp
Warehouse - ware2.bsp
Main Gate - jail1.bsp
Destination Center - jail2.bsp
Security Complex - jail3.bsp
Torture Chambers - jail4.bsp
Guard House - jail5.bsp
Grid Control - security.bsp
Mine Entrance - mintro.asp
Upper Mines - mine1.bsp
Borehole - mine2.bsp
Drilling Area - mine3.bsp
Lower Mines - mine4.bsp
Receiving Center - fact1.bsp
Sudden Death - fact3.bsp
Processing Plant - fact2.bsp
Power Plant - power1.bsp
The Reactor - power2.bsp
Cooling Facility - cool1.bsp
Toxic Waste Dump - waste1.bsp
Pumping Station 1 - waste2.bsp
Pumping Station 2 - waste3.bsp
Big Gun - biggun.bsp
Outer Hangar - hangar1.bsp
Comm Satelite - space.bsp
Research Lab - lab.bsp
Inner Hangar - hangar2.bsp
Launch Command - command.bsp
Outlands - strike.bsp
Outer Courts - city1.bsp
Lower Palace - city2.bsp
Upper Palace - city3.bsp
Inner Chamber - boss1.bsp
Final Showdown - boss2.bsp

Cheat Codes:

All Items in Single Player - give all (at Console screen)
God Mode - god (at Console screen)
Unlimited Ammo (version 3.14) - /g_unlimited_ammo 1 (after pressing ~ while in game)
Walk Through Walls/Fly - noclip (after pressing ~ while in game)
Allows you to set the gravity, where 0 is no gravity and 850 is normal - sv_gravity XXX
Gives you the rocket launcher - give rocket launcher
Gives you rockets, where XXX is the number you put - give rockets XXX
gives you the hyperblaster - give hyperblaster
gives you the BFG - give BFG
gives you X amount of cells, where X is the number you put - give cells XXX
gives you the item you entered, as well as in the quantity you put as X - give (item) XXX
gives you the weapon you enter in place of (weapon) - give (weapon)
gives you the ammo type you entered, as well as in the quantity you put - give (ammo) XXX
Enemies can't see you - notarget
200 body armor - give armor
1 jacket armor - give jacket armor
1 combat armor - give combat armor
1 body armor - give body armor
Turns on Infinite Ammo - dmflags 8192
Gives you the Shotgun - give shotgun
Gives you the Super Shotgun - give super shotgun
Gives you the Machinegun - give machinegun
Gives you the Chaingun - give chaingun
Gives you the Grenade Launcher - give grenade launcher
Gives you the Rocket Launcher - give rocket launcher
Gives you the Hyperblaster - give hyperblaster
Gives you the Railgun - give railgun
Gives you the BFG 10,000 - give bfg10k

Unlimited ammo without console code:

After opening the game, go to multiplayer. then Start a network game. Go down to the menu labelled 'Deathmatch Flags'. One of the options is infinite ammo. Select yes on this option, then start a single player game. You will now have unlimited ammo.