My 90's childhood trauma resurfaced here.

I pressed + a few times to keep making the horse bigger, which made me happy, and wondered "How far can I go with this?"

So I pressed it a few more times, with diminishing results, and then I started feeling anxious for some reason. I realized I was thinking "Wait, this is a setup. How long until it turns into a horrifying face and screams at me?"

Too many old gimmicky sites/flash games that cause users to focus more intently/rush on through before throwing in a jump scare. Always hated that stuff.

Based on the other comments though, I'm relieved it seems to be an innocuous site that just helps a horse achieve its dream of becoming as big as it can possibly be.