I didn't make it!
I'm not going to state that cheating is impossible in UT - no-one can KNOW that, but the examples given so far of 'cheating' are NOT valid: Jumping from shore to ship is easily possible ALONE and WITHOUT ANY HEALTH. Jumping great heights is similarly possible: With the aid of a team-mate (or even 2) with hammers - you can jump to the gun in OVERLORD from the back-end of either tower. One team-mate with 4 rockets can launch you (unhurt) the length of the whole map. When you feel that you SHOULD be hitting someone with shot, but are having no effect, this can happen due to many things: your connection speed, your game settings, framerates, lag etc. (honestly). After 10 years of playing, I know that there HAVE been cheats available, but they are soon 'shut-down' by the servers.
I have through the years left the game - because I believed that 'cheats' were ruining the game. It all eventually came to light that my settings were not correct.
Yes, there ARE 'secrets' - and you'll find these by playing the game and talking to UT'ers.
Get fragging and forget all about 'cheat-codes' - their are none.