Doeo is a game in English, based on a Japanese game called Moai no Su (click on the top option on the start screen in order to play). Try them both and you’ll see that they’re extremely similar, basically the same game with different dressing. This isn’t a coincidence of course, the Doeo dev has an explanation here, but it basically boils down to the fact that Moai no Su was a Japanese game in Japanese and popular in Japan but pretty well unknown among English speakers. So he made an English version.
So what sort of game are they? Well there used to be a genre sometimes called “arena shooters” back when light guns were common. That’s the closest analogue I can think of. Basically a bunch of things pop up and you “shoot them” (touch them) with your mouse. That’s it. In this case it’s the presentation which makes it work.
Like Z-Rox, Second Person Shooter Zato is appealing as much for being a different way of looking at things as it is for anything else. As the name suggests, the player is the focus of the camera and the game is played through the eyes of the enemies that you are fighting. This generates a nice split-screen effect when there are multiple enemies on the field.
On a practical level the perspective forces you to work in reverse to how you’re accustomed, much like performing a task while looking in a mirror. It’s a challenge in itself, and in the context of playing, operating under the gun, it provides an effective mechanic for a short game like this one.
On a psychological level it’s a little bit interesting to shoot towards yourself. This game, with its blocky cartoonish style, doesn’t play into that aspect, but there’s an older game, also called Second Person Shooter (no Zato), which did slightly more to explore this. Unfortunately, it doesn’t seem to be available any longer. All of the links that I can find lead to the same place, which is currently unresponsive. I’ll link it anyway, just in case it comes back to life, but you’re not missing much: calling it a full game is probably overstating it, more like a demo, and while it was interesting there just wasn’t a whole lot there.