I picked up the nearest competitors to Slay the Spire: Monster Slayers and Dream Quest. If you were to put them on a spectrum from “roguelike” to “deckbuilder,” Dream Quest seems clearly the most roguelike, Slay the Spire the most of a deckbuilder. Hearthstone’s dungeon run stands beside them as a mess of randomness that has elements of the two genres without doing much coherent. I am setting it aside for this discussion.
The frustrating thing about these two other games is the need to grind to unlock things. There are unlocks in Slay the Spire, but not just 6 for each class, and they are not necessary to beat the game. Monster Slayers and Dream Quest both have many unlocks, and you need to grind to have a chance at the later maps. A skilled player could sit down to a fresh install of Slay the Spire and beat it. I do not think that is mathematically possible with Dream Quest or Monster Slayers. There are just too many upgrades that you unlock.
Dream Quest was not a lot of fun, so I set it aside after what seemed like a fair test. Bonus points for having poor stick figure graphics that show what West of Loathing is doing the right way.
Monster Slayers is a better game, but it lacks an enjoyable beginning, middle, and end. If you have not completed enough unlocks, you cannot reach the end. If you have enough upgrades to reach the end, the beginning is trivial. It shows growth across runs, but within a run, the first half or so is of trivial difficulty, and you are just seeing how your deckbuilding options fall out. I am interested in seeing how the lategame looks now that I have enough grinding under my belt to get to it. At least the grinding is once overall then once per class, rather than needing to be repeated per class. Most of the upgrades are shared across classes.
Of the four implementations I have tried, I favor Slay the Spire. Please mention if you have seen other variations on this theme or deckbuilding games making use of the options that computers bring.