I have been trying for a month straight to make one and I've had enough. :-\
Everytime I take 1 step foward I take about 2 back.
I have one sorta working right now, its 3 minutes in length. The problem is I'm unable to make it loop. The other problem is that when Im entering a house the screentone doesn't stay the same... If any of you have a scropt or anything for me, you would be my god.
Strike 1, there's no scripts in RM2K.
Moved to RPG Maker Tutorials
Have you tried a parallel process and common events? Set the alarm every 3 minutes by toggling a switch which resets the alarm. Apply that to all maps and you got it.
http://rmrk.net/index.php/topic,25790.0.html might help :D
At the beginning of the events you want to loop, insert a label, and then at the end of the events you want to loop, insert the Goto Label command and reference the label you just created. For example, if you wanted to make a loop that did Action A, Action B, and Action C and then repeated the sequence over and over again, your code would look like this:
Label: 1
Action A
Action B
Action C
GOTOLabel: 1
Hopefully that helps. If not, I can give you the code I use for my day/night system, but it's a bit longer (24 minute cycle).