This game is simply glorious. Everyone else described the game pretty well, so I'll focus on the mods, which are IMO necessary nowadays. First you've got the 1.13, which is pretty much the base for every other modern JA2 mod, it's impossible to elaborate on it in this short review, but it changes, and more importantly, adds a ton of features, including paradropping on to the battlefield, covert actions, mobile militia and different roles for enemy soldiers and assassins. My personal favorite are mods based on AFS (Arulco Folding Stock), made by Wil473. There are three, aforementioned AFS, which is pretty much regular JA2 campaign with new weapons and gear. Then you've got Urban Chaos 1.13 and Arulco Revisited 1.13, which change the story and maps and are based on classic mods. Then there's AIMNAS, pretty much a constant work in progress, but a very impressive mod nonetheless, it adds massive amounts of gear, but the main highlight of it is the so called big maps project which changes tactical map sizes to behemoths challenging the capabilites of games engine. And finally, Straciatella Project, which basically a bugfixing and OS compatibility mod, doesn't add new features, but tries to iron out any problems with the base game and make it compatible with most modern operating systems. (Seems to me like this description doesn't do it justice, but I've never personally used it, only read about it) If you're interested, go to Bear's Pit, it's the main JA2 modding site, lots of really helpful and giving people over there and there's a couple of other mods to check out as well.
I played this game a long time ago and for a long time, haven't bought it yet on GOG, so I don't know about how it runs. HOWEVER! First sentence is not a mistake, I've played this with my father from 1998 till 2008 (Or even beyond that), we kept getting stuck in the later levels, which are incredibly convoluted, like Fairy World (Though very satisfying once you figure it out). Regardless, I'd still give it a top rating, simply because it's a lot of fun, especially finding new weapons and spells, and IMO it holds up well today. It gives you a lot of flexibility in regards of how you want to play it and, from what I can tell, all of them are feasible. Even the graphics haven't dated that terribly, same goes for the voice acting. I usually pay a lot of attention to VO and a lot of games from that era are very stiff in that aspect, here it sounds rather natural. One last thing, don't be me, don't think less of yourself if you get stuck and have to look up a walkthrough, it's really hard at times. Unless you want to spend a lot of time on it : D
