When I purchased Breachway, it looked like everything that I wanted from a Slay The Spire - like game. Replayability, a new setting, science-fiction, space battles, and perhaps a little bit more depth, and a bit more story. After playing other games in the genre, like Monster Train, Breachway doesn't stack up as well as Slay The Spire.
The first element is the absence of any music that drives you to want to continue playing. The soundtrack of Slay The Spire adapts based on how close you are to death, the risks you're taking, while in Breachway, when death comes, it comes quickly, and with no emotional pang of loss when you've got to go back to zero.
Breachway sees you put in charge of a spaceship. You can outfit it with weapons, crew it with characters who gain morale, and then give you special abilities that can give you a bonus during the battle. I found that these bonuses were rarely things that could change the outcome between death and success, and more along the lines of "I better remember to use this" - more often than not, to get things over with faster, because combat is slow, and it seems each turn there's a stutter while the game saves the state.
As a result, Breachway feels unsatisfying strategically and in terms of flow. Once you're done with a run, there's also no real incentive to go and play with your new toys that you unlocked on a given run.
Speaking of unlocking things, progression from run to run feels like it is designed to keep you playing for as long as possible, to give perceived value (in terms of hours played) - but the reality is the game's pace is too slow and speeding it up wouldn't solve this problem.
Ultimately a disappointing attempt to bring something new to a deck builder, and science-fiction into the genre - but something that still kept me entertained for almost a dozen hours.
The one boon is that it works great on Steam Deck and Linux.