Here are a few ideas that I have for both hunters and monsters alike.
Greatly increased ability damage, i.e. Rock Throw would straight incap a hunter if and only if it directly hit them at a 3 point rock throw. To make abilities not OP, greatly increased cooldown depending on the ability. i.e. charge would deal less damage but have a near instant cooldown as charging takes not real energy for a 10 ton killing machine. Wraith’s decoy would deal a moderate amount of damage with a 2 minute cooldown because of the physical toll taken to create of copy of yourself. Kraken’s lightning strike would straight up kill a hunter because ZAP! Would have an extremely long cooldown of like once every 10 minutes.
Monsters would have no armor but increased damage resistance and health overall. Monsters would be near unstoppable at stage 3 but would need more food. Hunters would need to be constantly moving as in real combat with an intelligent killing machine standing still and kiting would be useless if all it took was a well timed rockthrow to kill you. Monsters would have all abilities 3 point at stage 3. abilities would all be unlocked at start. i.e. Behemoth would have all four abilities but tongue grab would deal no damage because tongue. Monsters would be harder to track and neither party would be able to see a health bar of the enemy team. hunters would know each others health.
Hunters: greatly increased jetpack capacity, same recharge, more reliability. More damage to weapons, no auto reloads on all weapons, grenades/abilities not included. Things like Hanks Orbital would deal more damage but have and extremely long cooldown, like twice per game long. Hydes toxic nades would do damage to all hunters unless shielded, all explosives would do damage to hunters if fired too close. Same goes with monsters but to a lesser degree. Orbital could outright kill a hunter if a single bomb hits near them. Hunters and monsters alike would have to be careful of their health but hunters much more so. hunters could be ragdolled very easily and would take some time to get up based on class. Medic would health much faster and to a higher degree. No relay.
Wildlife: Only Tyrants, Crowbill Sloths, Megamouths, and Mammoth birds would outright attack the monster if it got too close at stage one. Nomads, Armadons and such would have to be provoked. Animals would deal less damage to the monster, more to the hunters so killing everything is advised. All predatory animals attack hunters on sight, have less health. No respawns unless Laz as OP said. No glowing tracks, no bird markers for hunters. anything would scare birds, even hunters. No carrion birds.
Feel free to add suggestions and give feedback. Having an ultra realistic evolve would be fun for hardcore players.