>>714437406
>like how does a infantry unit with 5 troops takes a city?
Don't think about this stuff too much, I saw a pic recently that debunked just this type of reasoning for HoMM (I think it was).
It doesn't matter that the treasure chest is as big as the mountain on the map, just that it looks good and is fun.
Suspension of disbelief will do all your heavy lifting if things are not completely stupid, at least when it comes to people generally.

>Is the best way to to figure out if a game idea would work or not is to draw it out or do you need to go further and make a demo?
It's a video game. the best way is to be able to play it out and have people try it, and actually change it if something feels like it sucks major balls or causes some legitimate problem.
Thinking and planning is good, but a solid idea that plays bad shouldn't stay just because it sounds fine.