Okay, for starters, I'm talking about that. Not the popular Spiderweb PC RPG series.
Okay. Yeah, I just felt like talking about this because it keeps impressing me.
basically, what it is, is a early-nineties/late-eighties Metroidvania game, with some neat minor additions to the basic formula, and then one really massive set of additions.
What makes the game so impressive is the physics, and how it's used. Every object in the game that can be interacted with is bound to the internal physics in the game. Gravity works on anything that can move, and everything you pick up has weight which affects how you can fly while holding it. Equal and opposite force is in play. All in all, it's very impressive.
But you know, it doesn't stop there, and I've never seen another game do this. almost every puzzle in the game relates back to the internal physics used. Even puzzles that don't, like... sometimes you can find alternative solutions involving using the games physics. Really, genuinely emergent gameplay. A walkthrough exists, but as far as I know, there's no major set sequence of events, and even when I had to look at this walktrhough, I've often found that I didn't like the solutions presented, tried something else, and got results.
Really big example. In one part, you have to go into this one area of the cave to get a key. The way you're supposed to do this is to get to some teleporter, shoot at some switch beyond it, and this switch changes the teleports target to the room you need to be in.
I found an alternate entrance. Said entrance opened to the planets surface, and had strong wind coming out of it. At that point, I had the jetpack booster item which lets you move faster, thus fighting against the wind somewhat, though not enough to really get into the tunnel. What I did was thrust down as far as I could and then let the wind blast me up, thus picking up speed, until I could eventually get down far enough into the tunnel. This actually didn't work. However, I DID find that the right wall had some weird slope to it that I could actually repel off of, thus keeping a steady downward motion going and not getting blasted out.
Really, really fascinating stuff. The fact that it was made in 1988 (Er, ST version I was playing was 1990 I think, actually. BBC version asn't much different) for BBC Micro is just amazing.