Just started playing a bit of Global Defense Forces 2 Portable (ie Earth Defense Force Portable 2). It runs surprisingly smoothly on PPSSPP, even on my crappy old android phone, and isn't too bad to control even with just touch controls instead of a gamepad.
There really is nothing else like EDF out there. It's made for grinding, it's made for killing swarms upon swarms of enemies (huge bugs and robots in this case) and it fits into the mobile genre pretty well. You lose a bit of the verticality of full EDF releases, mostly because it's hard to aim on a touchscreen (it'd be fine with a controller, and there is auto-aim for upsy-downsy aiming, kinda like Doom), and you only get two classes to play, but there's still all the city-wide destruction you could possibly hope for, all in gloriously janky 3D. Don't worry about the framerate, just keep firing. The wingdiver is nicely OP as well, so if you're worried about console touchscreen controls in a 3D shooter, you don't have to be. The wingdiver's basic weapons remove any problems such as precise aiming, etc, for you.
Anyway, I do recommend anyone that even remotely likes 3rd person shooters to give it a go. Or people that like killing huge bugs. Or giant robots. Or Kaiju. There's something for everyone. It's in Japanese, but it's such a simple game that this shouldn't really bother you (I don't read Japanese and I worked it out pretty easily). The weapon names are a bit of a mystery, but just try them out and see what works for you.
EDF! EDF!
(this game will probably never leave my phone. It's more cathartic then nearly anything else in the playstore. I wish I realized that EDF had a PSP release earlier, because it runs way better than a PS2 emulator would)
(for the settings I'm using on an old Oppo F1s, for 20-30fps on the FPS counter (so, playable, but it feels more like 15-20fps with the frameskip) :
Autoframeskip:on (for proper janky 3d)
Rendering Resolution: 1xPSP (save the frames, your phone ain't big)
Display Resolution (HW Scaler): Auto (save the frames more, let it blit it directly to screen)
Lazy Texture Caching: ticked (oks, might be a problem)
Disable Slower Effects: ticked (expect not to see the deathray that killed you)
Spline/Bezier Curves Quality: Medium (probably just makes you fall through the map sometimes, and does nothing for +fps. But might be funny anyway)
Anistropic Filtering: Off (every bit of gpu filtering you can get rid of is +fps. If anything, it ruins textures that were specifically made to be viewed at exactly PSP resolution. This is gold)
There's some weird thing that you can try and overclock the PSP core in the System menu. I set it to +302. It's completely stable. It may or may not do anything. Seems to average about 1-3 fps though on the counter, so it is a thing to do.
I only did this on mission 8, but have tested a few more. Not saying that they won't screw up anything on other missions. But it certainly upped the FPS. It's probably mostly from turning anistropic filtering off and putting it to 1xPSP resolution though.
That's from what I remember that I changed from the defaults. It runs better, and no glitches so far, and actually looks better in some ways than the default options like this. Huzzah! Crappy graphics chip and octo-core win, even without gHz or ram to back it!)
^note: it's not that an F1s is a particularly good phone, it's because a PSP is an easy chipset to emulate in some ways. But the original release can only be pushed so far, even it had toppling fps in many areas. You may be able to get "better than orginal" graphics quite easily off other, more decent phones. And better FPS than the original PSP could provide. And then cast them to your smart television over Wi-Fi. And then play them on a decent Bluetooth controller. It's a wonderful world we live in. But it'll only ever be "a certain amount of good". It was still on a PSP. There's limits.