Thoughts on this series and viability of playthrough with keyboard + mouse?

Why not ask in the subforum?

It's the J-est RPG series I own on gog, so I was confused when it didn't appear in the JRPG sale a while back.

I can't play it with keyboard and mouse. That doesn't mean it can't be played that way, though. Unlike some other games, you can at least configure the keyboard (and controller) bindings. However, you're just using the keyboard as an alternate gamepad mapping. I think all the help screens and prompts still use the Playstation button labels, for example.

The characters and story are weird, given that the characters are personified game console vendors and game developers. If you don't like that sort of thing (and I know many people don't), you will hate this series. I thought it was silly and amusing. The second game's protagonist was kind of whiny, though (and the story had a lot of heavy pro-DRM preaching), but the 3rd made up for it. There is no continuity whatsoever between the games (in fact, 3 retconned most of 1's events). The series is incomplete on gog, but you aren't missing a thing story-wise. In fact, you can just buy 3, which is the best of the series on gog*, and be done with it. There is a button you can press to skip most of the nonsensical story if you like, in any case. The DLC includes extra characters, so I'd probably get that, too.

If you're wondering about the pictures on gog's store pages, the 2D-looking ones are conversations/story, and the 3D pictures are the rest of the game. Interestingly enough, the pictures for 3 are all from the intro/tutorial mini-chapter.

I mostly like the combat system: a small field, pure turn-based, with turn order based on character speed and last performed action. No random encounters; all monster groups are clearly indicated and can be avoided or "surprised" (unless they are story events, but even then they are clearly marked on the map). The only other gog games I'm aware of with the same kind of combat are the Legend of Heroes Trails... series. Unlike that series, though, you can't save everywhere (but often enough, usually) and there are no NPCs outside of the main story: towns are just menus for shopping & such, and the world map is just a place to select the next dungeon.

The only bug I encountered was pretty serious, though: sometimes (very rarely, but more frequently in 3) an enemy would experience choice paralysis, and the only way to fijx is to kill the game and restart (made worse by the fact that you can't save everywhere). For all I know, that may just be me, though, due to playing the game in Wine on Linux.

* One thing with 3 is that they changed one of the core mechanics (combining the SP and EXE guages). Is it better or worse? Probably just a matter of opinion, but it does have a major effect on how you do boss battles and use special moves in general. If you want to try both styles, get 1 as well. When these games go on sale, they're dirt cheap, anyway (usually ~80% off).