I don't know how I missed this thread, but we did this back in the day as a kid.
Used 10 siders for percentiles, then had different distances for the weaponry. SICK isn't thwe word for what we had going on. it wasn't very fancy, but we started it because of figuring out how they shot at each other, and helped to try to minimise that "Hey I got you!!! NO YOU DIDN'T" routine. rolled the dice in a shoebox lid, and it would edepend on the weapon the numbers of the shots. We used a shoestring for the blasts, and Eye line of site for the action. Hand to had was sort of a hit/ miss thing, that we would have to call out thier fights, and it was more of a "Gentlemans Agreement" a lot of the time.
As to your terraign question, There are numerous options.
1. styro board, paint, hobby/ craft stores. Doll house kits, and inspiration from the past in sites that cater to G.I.Joe collectors.
2. Numerous options for playsets, either off the shelf, or on E bey. The options are endless.
3. Set up your battlefield, and design your own with plasticcard/ cardstock/ styro boards, and add in your own from any diy store.
I once made a playset out of wood, and other stuff that was the envy of the area. We used to fight with these guys all the time as a kid. My base streched for three rooms in the house, and I caught all kinds of hell for it from Mom.
Used old FM's for designing up the squads, and a bunch of old 80's era military books and magazines for the basis of the organization and equipments.
If it took a hit and dies, the weapon stayed in place, and the driver got something like a 50/ 50 chance of making it out of the wreck. We had lots of fun, and that stuff lasted a few years.
I still have a bunch of it, and the micronauts took the stuff to a whole new level. ( Back then, there were these sets of army men from MARX, that even today are legendary for the amounts of stuff you got for the price. The green armymen ended up being like cannonfodder in there. I had a main bad guy that I scrapped together out of different stuff that ended up really becoming a PITA to both sides.
COBRA ended up branching off and there ended up being a couple of different factions from a couple of guys down the street, and one from the next town over, who ended up doing stuff like pulling out an aircraft carrier, and some other moble game changers.
I had quite a collection of Star Wars guys, and Micronaughts, along with the Joes/ Cobras that ended up becoming sort of a fith and sixth faction. They were used quite a bit in different settings.
mmmmmm......
Those were the days alright. Might have to check out some of that old stuff again, when I get back.