There are so many flavours of tower defense.
I haven’t seen another TD game with a minimap yet, but I’ve seen them (like Defense grid) with a ‘forecast’ GUI that shows you what is approaching. I quite like the forecast bit, because it creates an emotion of panic or dread, and emotion is vital to games. I haven’t decided to implement a similar feature yet (and anyway it doesn’t matter for attackers), but I am intrigued by it.
Minimaps aren’t normally required because TD maps are often small, but mine are big, and I think a minimap is very handy, especially if you have a big screen and can afford the real estate. Plus, the minimap will toggle on and off anyway, so it would be silly not to put it in, as it’s all coded etc.
GTB has fog of war, so you can only see X pixels radius around your units. I like this, I like it a lot, but again, I don’t see it in other TD games. My variety is a constant FOW, so exposed areas return to shrouded entirely once the unit that illuminated them dies. I like that too, but YMMV. Right now you can toggle it off, but that may change. Maybe I’ll force it on when playing challenge maps.
GTB has instant building, so far…. I may change this. I know that it’s a big part of some TD games that you need to plan ahead and get those towers built before the enemies get close. I’m not sure whether I want to add a construction delay or not. Possibly….
I’m pretty sure there are a thousand other decisions like these, and as with all decent game design, you can never really know what the right decision was until you have implemented both ideas, tried them a lot, and asked a few opinions. Obviously that takes extreme time, and extreme effort. I’m beginning to see that having a nice spangly engine with cool explosions and effects is only a small chunk of making this game…