While reading the rules, I got a great Idea regarding combat, but I am not sure if it is even allowed so I am asking this question to clarify: 

So the combat system I tough of would require there to be no combat screen, instead it would be turn based and largely dependant on movement and strategy. You would be able to walk during combat and enemies follow use items and interact with them etc... It would be kind of similar to combat in games like Hitman:GO.

Are unconventional combat systems such as these allowed in this jam?

I doubt this would be a problem. In fact, it's not really all that unconventional. While there are ostensibly fewer DRPGs that use that kind of system than those that use more of a jrpg style turn based one, it's a pretty natural fit and is hardly unheard of.  There are also some hybrids around. Legend of Grimrock uses a similar movement model, but, instead of simultaneous moves, has it happen in real time. 

A simultaneous turn system along those lines is also not the worst to code, though pathfinding and AI are always kind of a pain, and this framework can end up being more structurally complicated. I made a prototype of this kind a while back, and I'm hardly the best coder. So if I can do it, it's probably quite achievable across the board. That said, if you want to implement it from scratch in under 8 days, along with doing everything else, it'll certainly be a challenge. 

But then, I guess that's kind of the point. 

   

I'm no judge but after checking how Hitman:GO works then in my opinion as is it'd be borderline and might not be allowed but after adding two simple nuances, first HPs and ways to lose HPs instead of exclusively instance death and secondly being able to carry and use consumables at will then it should be fine.

A combat layer separated from exploration sure is not required.