Roundscape is the most ambitious, and most expansive of their games. It does suffers from bugs, and some disjointed coding/work. However the sheer size/playtime, variety of fetishes, and abundant 2D artwork is great. I'm slightly biased, as I have hundreds upon hundreds of hours into the game. So I will say RA is the best of all the games so far.
Below Sunshade is a spinoff story within the world of RA. It's more of a survival management game, that's fairly short. The artwork is decent, it's similar to some of the artwork in RA. But I'm personally not the biggest fan of some of the characters.
Uprising is an abandoned 2D superhero game. I've never played it, but from what I've seen it's a about 6 hours long. The devs are working on making a new version of the game in 3D, called Project Uprising. It will be a long time before that gets worked on though.
Arenus is the main game the devs are working on. It has some of the most advanced artwork I've seen for a RPGM game. It's a little buggy as they are still working on it/play-testing. In fact some of their artwork and game content is too ambitious that RPGM isn't able to handle it properly. It's a little more than a demo at the moment, and a long way to go before completion.
Feel free to check them out, and come up with your own opinions, on F95Zone and Kaliyo's
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