The site that appears in the main menu of Learn Japanese to Survive! Kanji Battle (study-japanese.net) sells the games of the franchise.
And when I asked to the support staff about the presence of drm, they said the games sold in their site are drm free (e-mail attached as image).

ADDED, thank you!

The game is not finished yet, and you can grab its free demo from itch.io or Steam.
I think it should not be listed at #1 for now.

What do you mean by 'not finished'? I first played it years ago, and it worked perfectly. Great fun.

Oh, I have not played the game yet.
It is listed as "Early Access Game" on Steam, and their FAQ implied that it is in development now.

Well there's your problem.

Video games in development often provide free demo. It is very common, and some of them are DRM-free.
If someone can confirm that Cosmoteer is a finished game, I will add it to #1.
Otherwise I think it belong to some thread like "Free demo of games in development".

Try playing it. Once you have created a ship, you can fight it against other user created ships in intense online battles. No registration or DRM.

I'm actually quite surprised that it's on steam. It's obviously a very small indie developer, perhaps just one person.

There's no reason for it not to be on steam. It's much easier to get on steam than on gog. And there are, in all likelihood, many more DRM-free games on steam than on gog.

The issue here is not that it's on steam, nor that it's DRM-free. The issue is that the developer clearly marked it as an "early access" (i.e. not complete) game. All "early access" games can be played, so the fact that you have played it is neither here nor there.

It's up to kbnrylaec, as the list's maintainer, to decide whether to include Early Access games or not, and he has decided --- wisely, IMO --- not to.

I'm sure you're right. But it seemed finished to me years ago, and since then it's just been tweaking and adding stuff. Never did I feel it was unfinished or incomplete. Like I said. Try it before making your mind up.

AFAIC, this just reinforces my commitment to not trust anything steam says.

I don't think that's quite right unless I'm missing something.

Like mrkgnao stated, it's the gamedev who determines whether their game is "Early Access" or if it's complete - not Valve or Steam.

It's not steam who is saying it; it's the developer. The developer/publisher writes the information displayed by steam, gog, epic, etc.

That table is simply wrong.

Here is a slightly better list that lists more than 3000 titles:
https://steam.fandom.com/wiki/List_of_DRM-free_games
and even that list is known to be woefully deficient, as there are thousands of games that nobody bothered to inform the list maintainers about. I have been using steam for about a month and I am aware of at least half a dozen games not listed there.

If Steam indeed has 30K+ games, my uneducated guess would be that at least 20K+ of them are DRM-free. When people think games they tend to think AAA and AA games, but that's a tiny portion of steam's catalogue. Most games on steam are single-developer indie or small-studio casual games, I believe. And they usually don't bother doing the extra work of adding DRM.

One example: Artifex Mundi and Alawar are just two publishers of Hidden Object Games. Each has close to 100 games on steam, AFAIK all of them DRM-free.

Thank you for the link. I manually copied and pasted into Excel and there were 2860 DRM-free games, excluding software. And this also disregards the quality of DRM-free status on those games since some of them require you to edit text files or patch games manually to play them without the Steam launcher. If we were to remove 1.2 steam_appid.txt and 1.5 patchable games, together this is 283. So that's 2577 DRM-free games with similar DRM-free status as GOG. I agree, would have to get more reliable data. Though I'm quite skeptical about that estimate. If 50% of the library was actually DRM-free, I'd be surprised why news outlets, DRM-free communities, or even GOG forums wouldn't be reporting Steam as a more superior alternative to GOG. From a few searches, Artifex Mundi games are already included in the list. Alawar, no.

You're right. More than 2500 on the list, not more than 3000. I miscounted.