... you need to put some serious thought into balance.

In the workshop post for this you say that it won't be updated, but rather expanded upon once you can work with DOOM Eternal's assets.

Well, when and if you do this, consider the following feedback.

Bug reports:

• It's possible to double-jump indefinitely. I'm sure there's a double-jump mod in this pack and it seems to be broken. If you press space quickly, you can do four jumps in quick succession (which is already messed up). If you time your space presses slowly you can keep jumping indefinitely and ascend to the heavens.
  
• Keyboard keys in pop-up tips when you get a new ability are hardcoded and don't reflect what's set in the options. Also, they disappear a tad too quickly.

In general:

• You're trying to replicate DOOM's gameplay loop with Serious Sam's level design and, most importantly, enemy amounts. This doesn't work. Reduce the amount of enemies and beef them up if necessary.
  
• Enemies frequently spawn behind the player in corridor sections. As per the first point, this doesn't mesh well with the linear nature of SS's level design, and leads to unfair deaths.

Enemy specifics:

• The range of the Hell Knight's ground slam is way higher than the animation leads the player to believe. Reduce it to match the visual.
  
• Lost Souls are, simply put, broken. They track you through corners and turn mid-dash. Almost unavoidable in many situations.
  
• The Revenant fires WAY TOO MUCH. It's overwhelming.
  
• Possessed Soldiers also fire too much. In DOOM 2016 they do bursts of 4-5 shots. Here their weapons seem to be set for full-auto.
  
• I understand weapon mods probably won't make an appearance, so please gives an alternative way to destroy the Possessed Security's (I believe that's their name) energy shield. Grenade, maybe?. In DOOM 2016 you can do this by using the Stun Bomb mod on the Plasma Rifle. Here, only the regular ammunition has an effect on the shield and it takes way too many shots to go down. Also, I feel the fire rate of their weapon is a bit too high.

Weapons:

• Chainsaw: clunky. The target appearing should mean the player is in range to get a kill, but many times the animation plays and nothing happens. I understand a glory kill may be too big of an undertaking or just straight up not possible (although BFE has melee finishers, so I think it is), so ignore the range factor and just simply kill the the targeted enemy.
  
• Plasma Rifle: Not enough ammo pickups (wouldn't be that much of a problem if the Chainsaw worked reliably).
  
• Not necessarily a problem, but Super Shotgun: Enemies hit with the meathook get ignited and drop armor as if hit by the flamethrower. Is this the intended behaviour (not complaining, just seemed strange)?.

Just to be clear: what you did here is seriously impressive and I like it vey much. It fails, however, to capture the feeling of being in control, even when outnumbered, that the recent DOOM games provide. There's just way too much going on at any given time, because the level design was not intented for the gameplay. This overwhelms the player and eventually just turns into frustration.

If you can address the things pointed out above, while adapting the level design to account for the player's upgraded mobility and enemy behaviour, a potential full release of this mod will be 10/10.