Changing the computer clock won't affect the computer itself in any way, as you say. It will affect the game, in unpredictable and usually bad ways. Feel free to mess with the clock, but don't come whining to LDW or the forum if the game is spoilt. If you must, use a computer not connected to the Internet.

Most apps are not time dependent but some of the most important ones are, such as AV software checking for updates. I've also got a relatively simple program installed on my machine that shows TV schedules for the next few days. I don't want to check what's on then find out that it won't be shown in fact until 10 days hence.