"Clock" The clock is honestly useless. You have a clock in the corner of your computer screen.
"Day/night system" I believe I used DNS by prime_dialga in my Emerald hack and it worked fine. Use DNS definitely, though. I can't figure out how to use the seasons part of it, though. It requires you to make tilesets for each season, which is difficult.
"Why are the maps so small" Go into the header in Advance Map and you can change the map sizes..
The Clock isn't useless, without it, how are you supposed to evolve Espeon/Umbreon,dustox/beautifly? Without the clock, the day/night system won't work. Plus, some people are playing these Rom Hacks on emulators on our phones. I have a Xperia Play, and it has controller buttons.
I meant why are the maps small in people's rom hacks? If you have the power to change it, why wouldn't you? Is it a bad gameplay mechanic? Does it make the load time longer? What are the benefits/detriments?
The nostalgia was graphical and audio-centered. I feel nostalgia when I play red/blue/yellow because of the 8-bit sounds and pixel graphics. I didn't feel nostalgia for firered or leafgreen...