Ravana is lacking in the head department: he should have 10 of them (his birth name, Dashagriva, literally means “demon with 10 heads”). It’s probably the most famous aspect of him, and it’s disappointing to see that they ignored this. I understand why they did this, as the logistics of making and animating a model with 10 heads and 20 arms (by the way he has 20 arms) would be incredibly painful, but they could have tried to reference this in the model in some way. Rakshasa (the Hindu equivalent of demons) are depicted in a variety of ways throughout different myths, and are usually fierce looking (check) and with tusks (check).
The idea of an all-pervasive life force is quite a popular idea; the most well-known are chi (or qi) and its east Asian variants, mana (it’s Polynesian), the Native American (specifically the Iroquois tribes) orenda, and od, from Germanic Europe. The idea of being able to manifest this as spiritual power is also very common. The fact that Ravana does this is only stated explicitly in one of his ability descriptions, but can be implied with the other. While this is not shown in the Ramayana, it makes sense, with Ravana being a devout follower of Shiva, as well as a scholar.
They got a lot wrong here, but a decent amount right. Firstly, they attempt to reference the ten-headed thing by having Ravana decapitate himself 10 times (after all, death is more of a suggestion) in honour of Shiva to gain immortality, and instead gaining a boon (the boon is the same as in the original story). In the original story, he cuts of all his heads, just to show Shiva how devoted he is, he gained a form of immortality from Brahma (who happened to be his great grandfather) after either 1,000 or 10,000 years of penance (people disagree), who concentrated the elixir of immortality in his naval and gave him a boon (no deva or rakshasa could kill him). Hi-Rez then describe him as: “A master of combat, a genius scholar, a peerless leader, and now invincible…”, which is essentially the agreed upon image of Ravana. Unfortunately, they then state how the monkey king was unable to defeat him, however, in the Ramayana, the monkey king Vali immediately headlocks (headslocks?) Ravana, at which point the fight is over and the two become friends. The last part is about half and half: Vishnu did reincarnate as Rama to deal with Ravana, who at this point had pissed several minor and major devas, but they do forget to mention that the only reason Rama went to war was to rescue his kidnapped wife: Sita, who was only kidnapped because Lakshmana (by the way, Rama has a brother called Lakshmana) cut off Ravana’s sister’s nose.