Prior to 3.1.x the dat subdirectory didn't exist yet but data.base was present somewhere, possibly in the src subdirectory instead. I don't know whether it goes as far back as hack 1.x or even nethack 2.x. The source code for a bunch of old versions is present at https://nethackwiki.com/ but I'm not sure whether the data files are all there too. The source code for the most recent released version (3.6.7) is... Source: 12 months ago

I am not sure what extra benefits the Steam version has, but the game is available for free either as download on nethack.org, or to play online at something like alt.org/nethack or hardfought.org. Source: about 1 year ago

You don't even need two people to play D&D, Nethack is great! Source: about 1 year ago

I've always been fond of the last quote on nethack.org. Source: about 1 year ago

It was discussed here last fall, when the home page for nethack.org was updated to mention it. The blurb includes a few other tiny screen shots and says the exhibit is scheduled to be open until mid-July. Source: about 1 year ago

{ "id": 0, "name": "Guy Spelunky", "description": "The protagonist of the Spelunky series. This sprite pulls from his design in his debut game, now referred to as 'Spelunky Classic.'", "website": "https://spelunkyworld.com/", "subreddit": "/r/spelunky/", "center": [ 872.5, 513.5 ], "path": [ [ 867.5, 518.5 ], [ ... Source: about 2 years ago

Hell, games would still be made if there was no games industry at all. Free open source games are a thing. And there was a time, not so long ago, when people were just making experimental games for fun and releasing them for free. Games like Spelunky and Sky Rogue started out as free games made by hobby coders. Cave Story and all the Kenta Cho shooters are still free to this day. Source: about 3 years ago