Thick As Thieves puts you in the role of a thief in Kilcairn – which can only be described as a bleak and eerily magical version of Scotland — where a mix of industry and fae trickery has left the streets ripe with magical security and able, yet disembodied crews.
Your main goal in Thick As Thieves is to steal specific objects, as listed in the quests, and then to get out with the loot and return to your base. Gems, urns, treasure, riches it’s all open to be plundered and once you’ve grabbed the named items a timer will start as you and your friends race to the exit and secure your ill-gotten-gains.
At time of writing, Thick as Thieves gives you the choice between two classes, The Spider or The Chameleon, each of whom is sporting their own skills and equipment. The Spider comes with a grappling hook to help ascend buildings quickly, with a re-usable grapple that needs to be cranked back into position. The Chameleon does exactly what you think, he blends in and is able to walk past guards using glamour, although the more robotic security components are not so easily fooled. As you might imagine, these two make great cornerstones for a stealth-action heist game.

The guards are a mix of humans (both with or without torches) as well as some more ethereal and annoying ghosts that can home in on your position through walls. The human guards can be physically taken down, but the ghosts hurt you if you get near so it’s best to stay away where possible.
One of the current issues with Thick As Thieves seems to be around these floating, etheral guards, as they seem to be very sensitive to noise no matter where you make it. In the manor level I was in the basement and stepped into a puddle, a ghost three stories up seemed to hear it and float out of the ceiling to see what was going on… which seemed a little extreme.

Another thing to point out about the guards is that if you knock one of them out they don’t stay down permanently, they seem to periodically get back up and carry on as if nothing happened. Even if you manage to sweep up behind them after they’ve spotted you and give them the ol’ sleep tight, night night chokehold, they wake up down the line without a care in the world and start patrolling once more. Considering lights, drones and anything else that you can toggle on/off seem to stay in the position you left them, this also seems like an odd choice and makes travelling through previously cleared areas feel annoying and repetitive.
The actual thievery in Thick As Thieves is also very simple, with you wandering around and picking up everything and anything that isn’t nailed down. Most missions require you to steal specific things, which you use your gem to highlight. This is essential because the more important side-mission items of the missions are often difficult to tell apart from some of the more regular loot
I didn’t get a chance to review the included co-operative level with friends, but it’s very clearly made with other people in mind. With such a large map, lots of loot and a mix of possible abilities and equipment this would likely be a fun (albeit short) spat into a life of crime where you can break off and heist away, but the solo experience here is quite slow and gets a little stale after you’ve looped the same property a few times.

The tutorial of Thick As Thieves is a must play and does point out that you can gather clues to help find the more important items but even so, some of the locations can be a bit large with no real specific areas for the loot, I found a side objective item just next to a bush in a courtyard at one point which was frustrating as I was venturing onto every balcony or point of interest looking for it.
A similar game, with less magic and more crime would be Crime Simulator, although this has been around for much longer, it offers a similar experience in smaller but arguably denser worlds and has you try your luck against guards and civilians to meet your thieving quota for the week.
I also think that Thick As Thieves would heavily benefit from having some levelable skills, something that makes you move more quietly, or take down enemies faster to add that extra level of customisation as currently the roster is lacking in the upgrade department. I’m currently sitting on about 30k cash but nothing to spend it on as most of the unlocks are tied to progress and levelling but you don’t earn a bonus if you’re not playing co-operatively which seems like an odd choice to penalise someone with.

Overall, Thick As Thieves is a simple co-operative game about robbing the local rich/magical guys blind, you break in, you pick stuff up, you get out and unfortunately there’s not much more to it currently, with a loose story interwoven between the two available levels it is lacking in content but it does mention this is only the beginning on it’s Steam page so maybe there’s more to come down the line.
If you’d like to get your mitts on some stolen goods yourself you can check out Thick As Thieves on PC.