First clear evidence of that kind of plate+mail armour is from half of 15th century Persian sources, plus other much earlier references (although no 100% sure). It's not something distinctively Ottoman (apart from Middle East, it had quite some success also in the Indo-Persian area). And quite a lot of the armour already in the game is of the15th century type, so it's perfectly in line with the rest.
Plated-mail itself is at earliest in second half 15th century which I think is already very late for rest of what is used in this game since the armour in the game is not 15th century at all but 12-14th century. European 15th century armour would be full plate armour which I didn't see in this game. Moreover the one he is wearing is a distinctively disc plate which doesn't exist before 16th century in that form and except in Ottoman Empire, various other forms of disc plate also exists in 16th century in Russia, Persia and India. It's a type of armour made in compromise design with appearance of gunpowder weapons in the field, comparable to European breastplates. The type of vest he is wearing is also Ottoman in appearance and so is his sword.
In fact, I would be willing to bet the artist used one of these pictures as the reference, which is late 16th century Ottoman:
Regardless, I think the theme and general aesthetic of this game is clearly and distinctly high medieval with influences from fantasy and history before with very obviously pre-gunpowder era arms and armour. So including post-gunpowder type of arms and armour breaks the coherence. It is like including 12th century crusader in mail and bucket helm side by side with a tercio pikeman in breastplate and morion helmet, very anachronistic and nonsensical, as former was meant to protect against cutting weapons and latter was made with firearms in mind.