While some games nail down every variable so thoroughly that they feel more like interactive slideshows than artificial playgrounds, many games, sometimes entire genres, are built up around the notion that the computer can create some degree of novelty every time, through randomness, reactivity, and hidden information. Deep Sky Derelicts is a subset of these genres, a dungeon crawl in space that provides random loot, a card battle system, and random derelict layouts with several substantially different classes for your explorer team, all alongside structured missions. As with any system with enough variables, Deep Sky Derelict's experience comes down not to a list of features but how the whole system actually functions over time, which we'll go into below.
After creating a team of three characters from a list of classes and getting a debriefing from the head of a space station, players are thrown into the game with a few smaller, easier derelicts to explore, looking for the navigation computers that will point toward more derelicts and the game's end. Early on, hazards are limited to the monsters you find there, a mix of machines, zombies, aliens, and fellow derelict raiders. There are also incidental quests you can pick up by talking to people you meet or a sometimes updated mission board on the space station. As you explore rooms in a derelict, done through the game's map screen, your energy reserves run down. When they reach zero you start to lose health. If your team is wiped out in combat or from lack of energy, unless you're in hardcore mode you will get to reload, either from manual saves between battles or the autosave you get whenever you enter a derelict. You may also reliably refill some energy using up spare tanks, a few encounters, or sacrificing items.
The turn-based battles are frequent enough that it's good they can often be satisfying, and a good portion of the character skills and abilities directly influence combat. Character abilities are based on class, and, to a greater extent, equipment. Each piece of equipment and up to two mods for it may add ability cards which are drawn into a hand for each character at the start of battle and increase by one card per turn. Deck management strategies found in other card-based games are useful here, such as not having too large a deck that you won't conveniently be able to get the cards you prefer, and some have search abilities that can be used to reduce randomness. Enemies also use cards, invisible until you see them used, so they won't always be able to do optimal attacks, lending a great deal of uncertainty and tension to a battle. Certain classes lean more heavily on melee abilities, while others more on ranged or psychic attacks, and in addition to cards equipment can also enhance attacks in many interesting ways, giving you a chance to instantly kill minor enemies, get extra hits, cause status effects, area effects, reduce target shields, and have a chance to prevent discarding a card once it's used, among others.
While the start can be rough for those unfamiliar with the game, the difficulty ramps up substantially the deeper you go. A new derelict may mean that enemies have a lot more hit points and shields to slice through. Damage reduction, armour, evasion, stun effects, and shield regeneration (as well as bad card draws) might lead to round after round of stalemate, especially if you're behind in equipment and levels, and we had a few battles where an enemy was regenerating shields faster than we could cut through them, so we had to wait until it played the wrong card to finally kill it. Early on, the player's ability to survive is curtailed by a lack of income from salvage and missions, low energy reserves, and poor equipment. Allow for judicious retreats if you can't handle a battle, and perhaps a restart or two before you get a handle on the game's economy and skill system, especially if you can't afford to revive downed crewmembers in the medical centre (replacement crew can be hired, but it costs more to hire somebody than it does to heal the person you have, strangely enough). The game's energy economy also has to be managed through upgrades, as does the efficiency and effectiveness of scanning, which reveals the map and creatures within, an indispensable tool in the later stages when there are hazard zones that affect battle rules and monsters you might want to avoid.
The difficulty curve starts out a bit tough with all this early-game uncertainty, but as you get a handle on things it becomes more about figuring out how best to beat enemies with much higher hit points and damage resistance, making character builds perhaps more specialised than is possible for you unless you've retained a lot of the nicer weapons and tools that have abilities that might help. A big problem in the game then winds up being inventory management. If you sell most or all of the equipment you find that isn't worth upgrading to, you may have to dip into your cash reserves, if you have any, to buy mods that might help with a creature ability you hadn't anticipated. If you have a lot of contingency equipment your inventory will fill up quickly and become increasingly hard to navigate, even using the sort function. Equipment comparisons have to be done one click at a time, and while some screens give you a lot of information on abilities, others give you little, requiring multiple clicks and mouseovers to get information that should be available at a glance. We found we dreaded going back to the space station, as it meant often spending more time than moving through the derelict just sifting through items.