thats true 1000000%
look at the internet for example

Ouch.

Are they from some game?

Maybe, but it would be a game adaptation of an anime. While it is an OC, the base Kyubey is from Puella Magi Madoka Magica. It was the shows "mascot" and also the creature that girls would have to make a contract with to become a Magical Girl! (TM)

There was a webcomic I used to read called sparkling generation Valkyrie that had something like this happen. Though I have to admit I've never seen whoever show your referring to sadly

Highly recommend the anime but if you lack the time and just want a quick rundown there are three movies. The first two just recap the anime and while it shorten the series a bit you can still get a full rundown of what is happening. The 3rd movie is it own thing that require the context of either the first two movies or the series as it originally aired. So even if you go with the series you still would want the watch the 3rd movie at some point anyway. Saying what it is exactly about will spoil the main thing why people like it in the first place. Even if you might not be into Magical Girl stuff it still a high recommend for what it tries to achieve.

Wow what a pessimist.
Cute but terrible attitude.
6/10

True.

Have I seen this creature before?

I can't remember

So we do a...good job? Cool.