Is the gaming PC worth 300 euro?

Enough to be able to play Minecraft fluently and other games (if any). Please no answers like "build yourself a" I'm looking for a used low budget pc

Minecraft definitely yes, the other titles in principle synonymous - for 60 FPS but probably not on maximum settings, the graphics card has in the worst case, only 1 GB of graphics memory.

(by the way: I played a few titles back then on an i5-2500K and a GTX 660 Ti, it worked pretty well - but not on maximum settings)

Since the first question comes up for me, from when I liquidate Minecraft for you? 30FPS, 60FPS, 120FPS etc.

Since I had such a similar PC some time ago, I can tell you that you can probably play Minecraft with 90+ FPS. Are you doing even more mods in, etc. It may be critical to keep 60+ FPS for large modpacks, but in theory this is possible.

What else can you play with it? Well, there are a lot of games.

CS: GO, League of Legends, GTA V (low settings) should also be in there. Fortnite will probably not be feasible or only with low FPS which is not very advantageous in a fast game, especially in PvP.

Even if you do not want to hear it, if you used the parts singly / buy new you are cheaper than if you buy a calculator completely.

I can't say anything about the CPU, but about the GPU.

So I had early one with comparable performance (HD 6870). Will probably deliver BeO high settings 30-40fps.

But Minecraft is of course no problem.