Slay the Spire First Run Winrate

A question came up in a discord for Slay the Spire - what is the win percentage of players in their first time playing the game? I thought that was an interesting question, so I looked into it using the big dataset from Mega Crit, the creators of the game.

Overall, players on a first-time run win about 9.6% of the time.


My database is a subset of the full 77 million+ run set, containing mostly runs from after Watcher was released, when the game was near its current state. My database contains 18,209,495 runs total.

From there, I removed runs that are from beta builds, endless mode, daily mode, or chosen-seed runs. The vast majority of the remaining runs are from builds 2020-01-27 (Watcher update) and 2020-07-30 (the language patch).

From there, I counted runs where player_experience = 0. One thing to note is that this means the first time an account has played a run, not necessarily the first time a person has played a run.

Patch Wins Losses Winrate
2020-01-27 2,069 32,357 6.0%
2020-07-30 8,357 76,709 9.8%
Overall 10,426 109,066 9.6%

The all-character winrate at ascension 0 is 9.3%, so I find it interesting that the "average" A0 player across all characters is a hair worse than the average player on their first run.

I think this is due to at least two things:

  • The first run is simpler, in that there are less card options in play, and the boss events are scripted.
  • The first run is with Ironclad, which has a higher A0 winrate than the other characters.

The Ironclad winrate at A0 is 10.7%, so at least that right-side up.


Winrate difference

The winrate difference between the builds is surprising to me - I think the language patch didn't affect gameplay. If the game hasn't changed, this is very unlikely to have occurred by chance. A chi-squared test puts the odds of that difference occurring randomly at less than .001% (p-value < 0.00001)

Non-Ironclad runs

Normally, the first run when you play the game is with Ironclad, since none of the other characters are unlocked yet. However, the dataset contains 337 Silent runs, 105 Defect runs, and 60 Watcher runs where player_experience = 0.

Other builds

My dataset only encompasses post-Watcher Spire. The consensus is that for high-level play, the game has gotten easier as patches and tweaks have made their way into the game. It would be interesting to see if the winrate for beginners has changed over time as well.

If you have any ideas, please get in touch to let me know!