Cheat Mode
Add the "+set developer 1 +set sv_cheats 1" command line parameter. Press ~ during game play to bring down the console window.

Spawn item: give (item)
Full health: give health
Save game: savegame
Load saved game: loadgame
Get all items: give all
Ammunition: give ammo
Invincibility: god
Ignored by enemy: notarget
No clipping: noclip
Fly mode: ufo
Teleport to a specific map node jumptonode
Play indicated map: map (map name)
Suicide: kill

Play level of your choice
When in a Single Player game bring down the console with the "~" key, and type the following to play any level and mission you want.

Effect - Code

Play Mission 13: Kharkov 2 - map kharkov2
Play Mission 12: Kharkov 1 - map kharkov1
Play Mission 1: Bastogne 1 - map bastogne1
Play Mission 2: Bastogne 2 - map bastogne2
Play Mission 3: Foy - map foy
Play Mission 4: Noville - map noville
Play Mission 5: Bomber - map bomber
Play Mission 6: Train Bridge - map trainbridge
Play Mission 7: Sicily 1 - map sicily1
Play Mission 8: Sicily 2 - map sicily2
Play Mission 9: Trenches - map trenches
Play Mission 10: Ponyri - map ponyri
Play Mission 11: Kursk - map kursk

Rapid fire
Use the following trick to shoot multiple shots at once from a semi-auto gun (for example, Gerehr 43 or MP40). When you are sprinting with one of these or other guns, rapidly click fire (default is the Left Mouse Button). When you stop sprinting,
continue to click. When you are done sprinting, the gun should shoot three round bursts very fast. If it is a machine gun like the Thompson, it will fire extremely fast.