Divinity Original Sin is a pretty interesting game, although it is mired with a few annoyances and badly implemented ideas that make the experience less than ideal. It is, as they advertised, an old kind of game; turn based RPGs aren't that common anymore and the bulk of its mechanic feel like they have been designed a while ago. That being said, the combat system salvaged it for me after a while, otherwise I would have been ready to write this game off.
After a quick tutorial, you are thrown into the world with a quest about investigating a murder. You also get many other quests from various NPCs in town and you can talk to everyone about almost every new thing you find. Sadly, this makes the beginning of the game pretty lame, you start with a few tutorials and puzzles, but then its hours of dialogue and walking around, figuring what to do. The quest log is written as if the characters were writing it, only giving you cryptic hints of what you should do, without specifics. It gives the game style, but it also pushes looking online for solutions if you're stuck.
After you've slogged through these first hours and finally leave town, the game picks up - but its quite hard to do so. D:OS has a pacing problem and a speed problem. You move abysmally slowly outside of combat, the map is huge and there is nothing to do besides watch your characters walk from point A to point B. There is a way point system, but you cant go back from where you were so the way from town will be quicker than the way back. You also need to stand around doing nothing if you want to heal between fights - its likely than one of your party members will have a healing spell - but there's no fast forward, you heal yourself and wait for the effect to tick and the cooldown to refresh. Adding a fast forward option and/or a rest option would have been nice. Also, these damned NPCs with the dialog that repeats each five seconds or so, why are they like that?
Otherwise, the core systems are great. Your characters have main stats, skills, feats, abilities and gear, giving you plenty of ways to customize them. You also get personality effects from discussions, but I wish that the game would show you the results - and its effects - before you make your choices in discussions. By wanting to get the best effects for my characters, I have to save/load before conversations, hardly ideal. Stats affect many aspects of your characters, skills are used for things like the number of ability slots you have, the damage you deal with weapons, how good you are at crafting, etc. Feats have game-changing effects and often come with negative balancing side-effects too, which works well. You have plenty of gear choices, but the inventory system is clumsy and cluttered, even more so if you add the crafting system - drag two objects onto each other, if your crafting skill is high enough, they might combine into something - so I just took it to sell everything I wasn't using.
In battle, you use action points to move, equip items, attack or use abilities. You can bank them for future turns also, which allows you to plan cool combos. Abilities are divided into multiple families, witchcraft, fire magic, melee fighting, archery, etc. Each family has some specialties, be status effects, healing, or simply shooting arrows. The abilities are well explained, although its tough to see sometimes what their side effects are. The game has a neat idea about elemental interactions, fire makes oil and poison explode, lightning turns water into stunning traps, rain douses fire and so forth, but I feel like the game tries to make it too obvious sometimes with the bunch of exploding barrels placed around poison zombies, or some similar setups.
To conclude, D:OS isn't really a multiplayer game although it was marketed as such. I've tried playing it with friends and while the combat is fine, everything else is not as fun. Only the player talking to an NPC will see the text, the other one will see lines of conversation flash by. You have multiplayer discussions, but they amount to the same as you can do in single player. Also, it's a bad idea to play text-heavy games with others, especially if you have to skip the text because your friend is just going forward, but your mileage may vary.