Hmm, that actually looks interesting! Now, as for a few anime that might not be popular that I know...uh.
Okay, so if you somehow have enough free time to watch more than 12 episodes or can watch about maybe 20 episodes of something, there's Bomberman Jetters, an anime I remember watching many years back on Youtube. It was only a few episodes until I stopped. You gonna have to find it on sites like Kissanime, since it has never had an official English sub or dub or anything.
If you want to waste a few dollars for a short OVA, there's the Azure Striker Gunvolt OVA that's only available to buy on the 3DS eShop. I...have a hate/love relationship with this OVA. Just saying.
And finally, for an 12 episode anime, there's Seven Mortal Sins...also known as Seven Deadly Sins. It's only called Seven Mortal Sins because of the other anime called Seven Deadly Sins (the anime on Netflix). I actually liked Seven Mortal Sins, tbh. And no, it's not because the sinful devils are represented as cute girls (though that might be one of the reasons). It has a sequel/spinoff, but it's only on HIDIVE, which I didn't know was a thing until I looked it up when I noticed that Seven Heavenly Virtues wasn't on VRV.
Pick your poison! I am not responsible for any possible side-effects.