[Tyhm]

View the variables, the this.variables by NPC, the flags, and you can click any line of any NPC's code (at the far left) to put a break there, and it will stop there next time it's called, then you can add another one and take that one off and hit run and it'll go a chunk at a time, or you can use stop next call and the next button to go one line at a time so you can see where it's breaking, plus it shows you your script as the "compiler" sees it, if it stops suddenly it's because you left an error in the script.