This post is an in-depth explanation for the purpose of anyone who hasn't played the game and is wondering if it's interesting. Or maybe people looking for more explanation of the game than initially given, which is little. Spoilers ahoy because it's a long-ish post.
The game supports one to six players per server, with three "types" of maps: 1-2 players, 3-4 players, 5-6 players. However, these "types" of maps can be played with whatever amount of people you'd like. And I say "types" in quotation marks because they're all the same map, just with more or less things to repair, and that basically translates the maps to "Easy", "Medium" and "Hard" respectively. There are two solar panels to repair (and attached couplers and cables) on 1-2, three on 3-4, four on 5-6. One rover on 1-2 and 3-4, but two on 5-6.
Ingame controls are displayed with F1. Z is voice chat (not great quality, just like the voice acting). Prepare for slow walking speed. Bunny hopping may help, but to be honest, I'm not sure if bunnyhopping ever helps, I always use it anyway.
Alpha Moonbase is a welding simulator. That's it. Stuff is broken, and every single piece can be repaired by welding, unless completely destroyed, wherein you must replace it from equipment from the equipment shed. There are also some times where items are so severely damaged that it's simply faster to completely replace them instead of bothering to repair such severe damage (some pieces took up to 4 minutes to repair, in the 25 minute time period). Tools and robots (more on the latter later) are also obtained from the shed.
Most of your time will be spent welding, which is helped by a welding minigame, soldering two points while staying in between the lines of the circuits. Successfully completing the minigame, which will show up every maybe five to ten seconds or so while repairing can save you around 5~12 seconds varying on the difficulty of the puzzle given to you, seemingly at random.
The map is broken up into three main sections, the O2/CO2 production area, the solar panel area, and the coupler cable area connecting the two. All of them need repairs. Couplers can occasionally have critical failures which mean they are destroyed completely in a minute and thirty seconds unless they are repaired. The O2/CO2 production area -- the hardest area to repair in my short, one hour, experience -- has coolant leaks and must be repaired by robot.
The 'customizable' robots are either arm robots or welding robots. The customization consists of one slider to decide between a faster robot, or more battery. Arm robots can carry and replace equipment or function as a wrench (iirc). Welding robots... weld. The robots have an area of transmission, about half the length of the area you'll be repairing. So if you set up your robot at the solar panels, you can't repair the coolant area. And since the solar panels are easily repaired, just set up near the coolant area anyway. I've never had a problem with battery, I used one welding robot for about 20 minutes to repair the coolant area with the default 50% speed 50% battery, so as long as you place the robot near the coolant area, you may as well increase the speed some. Be wary of getting your robots stuck in the power cables, this was a minor crisis we ran into, and ramming robots to unstuck other robots didn't work much either. You can destroy, deploy, or undeploy the robot from the deployable controls (suitcase) you set up.
Once you start getting stuff repaired, a timer will appear to indicate how long oxygen production will take to restore the settlement to proper levels with the equipment you currently have repaired. Usually the ETA is more time than you get to finish the mission, so you need to repair about 95% of the stuff to win (unless you're godly fast and want to roll around in the rover for a few minutes enjoying your inevitable victory). Though 100% is always good.
There is also a rover which spawns a little bit behind you (and we only noticed at the end after exploring). It can carry two players, and what I assume to be one piece of equipment. It has a battery which seems to recharge when not in use, but you go such short distances this will never be a problem. There is also a command center we didn't notice until exploring which apparently serves as a sort of spectating area -- you get to stalk the astronauts via cam, and control the rover when it's not player driven (that overrides the remote control). You may think the rover useful, because vroom vroom is always fun and walking speed is tormentingly slow, but the time it takes to load on the item, enter the rover, exit the rover, and offload the item, let alone travel to the area, you probably are faster off walking there. The control center seems even less useful. You can spectate, or you can drive around the rover for no purpose, seeing how you can't offload and onload items, being in the control center and not outside. It's pointless.
Summary:Alpha Moonbase is fun the way it is, on the first match we just tried to figure out what we were doing for the first 25 minutes, on the second we actually completed it and were gradually already becoming bored by the end. The minigame gets a bit repetitive fast, as you'll surely notice. With more missions and more minigames this game could be quite interesting, but right now it'll only give you maybe a couple hours of fun-ish tinkering. Hardly mindblowing, but decent fun, if but for a little while.