I can't think of many thinks, which decrease Strength, especially by 10. Maybe Alberich curse stacks and you have given him 10 false offerings. That would show up in your journal under curses and blessings.

Or you have 10 Weaken spells on you, which did not get dispelled due to something like the Dweomer shield bug. But you would hear the sound effect in that case.

Maybe a bug, in which case you can use the follower editor to get your strength back.

Which version of the game do you have? Are you using any mods (like Arcanum Multiverse)?

I just installed the game on gog and didn't download any mods. It was working good until now.

You really should install UAP (Unofficial Arcanum Patch). Despite the name, it is very well polished and it's essential for moretheless bug-free gameplay, IMO. Maybe you just encountered one of many vanilla game bugs.

Seconding Kerebron. Download and install the UAP, and restart the game (a game in progress will not work well with the UAP).

Use this as an excuse to modify your starting character, or make different choices along the way. One of the appeals of Arcanum is its replayability: while the main quest doesn't differ significantly (unless you choose the side of good followed by evil, or vice versa) there are so many side quests, Easter eggs and dialog options — not to mention the magic vs. tech vs. thievery vs. fighter vs. talker, etc. — that a second game will almost never completely overlap the first.

Damn, I almost got 50 on that character, never been so far yet. I'll give a go to that UAP if you say so.

Then you may want to take the opportunity to also download and install the level cap remover hack.

The UAP already fixes one of the problems with the level cap, in that it allows followers to keep leveling even when you're maxed out. (In the vanilla game, when you're capped, they're capped.)

But it's so easy to get to level 50 before getting even halfway thru the main quest, that the game stops being fun for me unless I see myself continuing to make progress. And while there's something to be said for working within the parameters that the game's developers originally had in mind, there's just as much joy (for me, at least) in becoming as ridiculously OP as possible.

Sounds good, will do that too. Now I'm testing summoner build.

One more protip: there's a nice Easter egg if you learn and then cast Succor Beast with a full 100 MA.

Will check that aswell, thanks y'all for help!

Game became unstable after UAP. I even had to restart my PC once.
Ok so the problem is with my new character, a bandit. I wanted to create a bandit from Westerns, I called him Billy the Kid and train him in firearms but when I play this guy the game crashes like 3 times in 15 mins or so. Dunno what's the problem.

That is strange.

You installed only the UAP, and not the other patches (the high quality town maps and the high resolution patch)? There are known issues on some systems, especially Win 10, with the latter two.

If you did, uninstall those two and try again. Otherwise, try right-clicking on the Arcanum icon (the one you click to start the game) and add this to the command line (called the Target line in Win7):

"C:\GOG Games\Arcanum\Arcanum.exe" -doublebuffer -no3d -scrollfps:70

Note that the quotes are important. Also, if you changed your drive or directory from the default, then change C:\GOG Games\Arcanum to whatever that is.

The -doublebuffer and -no3d tags fix about 95% of problems with running the game. Also, it never hurts to make sure you're also running it as the administrator.

If the problem still isn't fixed, then we've reached the limits of my knowledge. Unless someone else comes along with a better idea, I'd have to say to delete and reinstall the vanilla version, with my apologies for getting your hopes up and (unintentionally, but still) wasting your time.

I installed only UAP since I don't like playing on higher res. I'll try your way to run the game and let you know, thanks!