That isn't suss at all. So I'm guessing the exe and bin file are some sort of zip self extractor with optional malware? Even if legit, it's annoying I have to break out wine just to get something which should not have been set up as a winders only thing.
If it bothers you that much I can post the loose files + the crack. The version I have is from steam and not itch.io, therefore it incorporates steam's drm. The drm must be circumvented or else the game won't launch and you will be directed to install steam/buy the game. There is no protection on the exe, so in this case a generic steam_api64.dll must be used instead of the real one to circumvent steam ownership checks and to run the game without steam. A txt appid is also placed in the folder since the generic dll needs to know what the steam application id of the game is.
The installer is from one of the few scene release groups left. The scene has been using iso's and installers for more than a decade. If you look at torrent sites and don't download from repackers (and compressers) like fitgirl, they're all iso's. I know it's scary downloading things off the internet, but this is what piracy of mainstream releases has looked like for an incredibly long time now.
That being said the game actually has a mac and linux version. I can provide you with the raw linux files and emulator (or a link to a site with a steam.dll generic emulator) ,but it may not work 100% with every game.
EDIT:
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The above zip contains the loose files with the crack already applied for people new to ISO's, or who are suspicious of installers. It has the latest update of the game on steam. I have no idea what was updated, but apparently it addressed some errors people where having. The file only contains the windows version of the game.