I think the easiest way to address the issues relating to the putative overpowered kicks, underpowered snipers, fast health regeneration et al. is to patch in a 'hardcore' mode for those who want a truly torturous challenge. This would be easier / less risky than re-balancing the game proper and perhaps making the game too hard for those who are happy shotgun spamming their way to Berlin.
- Reduce kick damage and only allow downed enemies (those who cannot walk / lack lower appendages) to be defeated with stomps
- Only a single enemy to be knocked down per kick.
- Skeleton enemies near invulnerable to kicks.
- Remove the ability to mash kicks out while player is under attack themselves / taking damage.
- Either increase damage on suicide bombers so that within anything but shrapnel range, a single explosion is lethal -OR- reduce their detonation time to the point where if they get within full damage range of the player, the player cannot avoid taking full damage by running away.
- Correspondingly, increase trap explosive damage on the players, so if within full damage range, the player explodes; even from full health, not only if already injured.
- Increase sniper enemy damage and allow them to head-shot kill players. The latter effect can perhaps be achieved by greatly increasing player vulnerability while crouched or prone -- head-shots landed while in these positions become guaranteed kill-shots.
- (If possible), allow for slow motion bullet cam from kill-shots made by enemy snipers on players.
- Increase perch positions for sniper enemies and randomise their patterns. Also, if the player remains in the same position, with their sights more or less trained on a known sniper perch, increase the delay for the enemy's return to this place (if at all; contingent upon available positions).
- Remove the 'first-shot' pattern of sniper enemies unless they can achieve a kill-shot (head-shot) to avoid their positions being given away before they even become a threat to players.
- Greatly increase mini gun(?) damage for ϟϟ sub bosses so that the player can only survive a single bullet from their weapons and that fighting them from range (and behind cover) is the ONLY way to take them out.
- Imbue fodder enemies with differing walk speed -- shamble, walk, run.
- hidden jump-scare enemies in story mode should only pounce when a player can reasonably be successfully attacked and said enemies should also attack aggressively; not flail and just stop / reset their pattern.
- Reduce attack delay time for said enemies so that walking up to them and kicking them is more risky and not feasible with
multiple enemies in close proximity to one another.