As much as I like the base game, Callisto Protocol stands as a premier example of how games are made for a certain difficulty. Dark Souls would not be so influential if it it did not have one default difficulty with which everything was balanced towards, be it in terms of relative health values, damage, speed of enemies, and so forth.
The biggest issue with Callisto Protocol on Hardcore or Contagion is that enemies are bullet sponges, and using bullets to take out the tentacles no longer works, at least with the handcannon. So the player is taught to not waste ammo on normal enemies that are just going to mutate into their tankier variants anyway, and melee becomes such a drag because every enemy will eventually mutate, even with a fully upgraded handcannon and baton.
Which by the way, less credits means that your GRP will be your go-to weapon whenever environmental hazards as investing the stun baton has diminishing returns, making enemies even tankier.