Finished that SaGa 4 fangame, and it's alright save for a few odd design decisions.
tl;dp -
Mechanically it's basically SaGa 1/2 while using assets from all 3 GB games.
Humans are stat grown like in 1, Mutants have some weird binary mutation choice occasionally after combat. Apparently one choice pulls from a fixed list, while the other option is context dependent (random NPC text from a third of the way through).
Robots and Monsters are basically the same as in SaGa 2.
Difficulty curve is basically this really odd U shape, as the getting started is as rough as it typically is in early SaGas while the endgame is marked by a rather odd increase in boss difficulty. You can run from pretty much anything but trap box/tile encounters, so your grind is very much YMMV. Everything up to the second to last world boss fight is pretty trivial.
By the same token, fight/monster/gear design is pretty flat? Yeah, you've got a variety of monster species and/or elemental weaknesses to target for one-hit kills, but you only ever reliably have access to undead killers and fire/ice/lightning weapons, and pretty much every boss resists weapon and primary element damage which then screws over humans and robots until endgame when Laser/non-element stuff becomes available.
Mutants are 1/2 Mutants, and can mutate Resist Weapon and Resist All (everything else). Like always, build em for Mana, stuff a Heal staff or Flare book in their hands and you're done.
Didn't run a monster PC in this, but the post fight meat prompt will tell you what result you'll get it looks like from the dialog window. There's also a couple of meat shops scattered here and there as well.