A hole in Steam’s API (patched now) allowed to see with precision the number of unique players for games with achievements (details here: https://arstechnica.com/gaming/2018/07/steam-data-leak-reveals-precise-player-count-for-thousands-of-games/).
According to this leak, as of July 1 2018 Thimbleweed Park has 98,491 unique players on Steam.
Other notable games (that puts into perspective the not so stellar sales of TWP):
Grim Fandango Remastered: 516,584
Monkey Island 2 Special Edition: LeChuck’s Revenge: 288,297
The Cave: 271,663
Day of the Tentacle Remastered: 265,169
Gemini Rue: 130,615
Gabriel Knight: Sins of the Fathers 20th Anniversary Edition: 42,031