It is a 3D RPG action game I played on Windows around 2010(not actual release date of said game)
Graphics are like okay(pretty much console graphics), characters are in real life proportions, a little bit dark fantasy themed, creatures are really more like designed(biomass, flying sentient crystals etc) than say those from nature(bear, lions, tigers, fishies, cats, dogs)
Main plot, character motives are unclear(I'm just an 8 year old back then), but I still remember part of the plot. Main character is a man with special abilities to summon Personas to aid himself in battle(no, not the Persona series). His persona is a giant(big ass) green cyanish coloured guy with buff muscles, floats in mid-air, fades in and out, punches so hard it has no mercy on enemies, it's ultimate skill is releasing energy bolts from its body and track enemies like missiles(screen also turns bright during the attack)
Near end of Level 1, you get a new relic or something like that, a swordsman guy that can freaking duplicate! But too bad, Buff guy persona has been separated into 7 pieces by a baddy and you're left with swordsman guy alone, so you have to embark on a journey to get back those 7 pieces.
2nd relic is a range attack persona, that's all I know sorry...
Now the game mechanics,
You are the player, has HP and melee weapon.
Persona, can be summoned by player, auto attack enemies, can lock on targets by player to gather fire. Has stats which could be boosted, special abilities and ultimate skill.
Persona also has HP and mana(for skill), when HP is depleted, Persona is retrieved and need to recover its health until full before ready to be summoned again. More than 1 Persona could be brought to battlefield but not more than 1 could be summoned at the same time.
Health and Mana potions are available.
That's pretty much all I could scraped out of my head, if you need more context, I could try my best to squeeze it out. Once again, thank you
Oh also, I think buff guy's name is Thanos