RTA stands for “Real Time Attack”. It usually means how long you took to run the run in real time.
LRT stands for “Load Removal Time”. It usually takes the time minus all the loading sequences that occurred in the game.
The moderators of a specific game usually will retime the run. To get LRT, usually an autosplitter via LiveSplit takes pauses/resumes the timer each time you go in/out of a loading sequence.
LRT is just the amount of time you spend actually playing the game, RTA is the full run with loads and whatnot. There is also no ASL, so everything is retimed anyways. Don't worry about getting lrt/rta correct, i'll just fix it when i retime any runs you submit.
PSA: On open combat missions there is a mandatory cutscene that you can skip through, (except on crash site that one is unskippable.) These must be part of the run. Any run that skips these to "save time" will be rejected. If a run includes this cutscene but then hits 'last checkpoint' to skip