Proof? Because I don't remember them specifically mentioning paid DLC's.
None of those games have hidden, unexplained core gameplay mechanics. Few examples: I approach from back I backstab, I attack I deal damage, I take damage I lose health, I increase attack damage I clearly deal more damage. Meanwhile in KP I still don't know why I'm taking more pleasure damage despite having high endurance OR why I'm still dealing same damage despite increasing dexterity or strength, depending on the run. I am willing to experiment if game is willing to give me information, I'm not gonna experiment on a PORN GAME WITH 0 INFORMATION. Here's a few games I experimented on and those are only the recored ones I bought on steam:
Stellaris: 271 hours
Slay the Spire: 62 hours, god knows how many more before I bought it
Xcom 2: 295 hours
MGSV TPP: 287 hours
DOS2: 253 hours
All of those games have CLEAR GAMEPLAY MECHANICS that go much beyond the depth of KP can ever dream of going.
-They mentioned the dlc but they say it COULD be paid, not that it will be necessarily iirc
-leaving comparison to other games aside , the mechanics ARE explained in the game, but you need to talk to npcs for it, it won't just infodump you with everything or give you a bigger tutorial
the guards room, the cafeteria(which you need to unlock via edict), every floor you cleared and the yard (which has more people added as you clear floors) . they all provide you with hints or straight up gameplay mechanics (guards room +cafeteria+yard even have symbols above their heads to indicate which topic it is).
to answer your doubts though, endurance does NOT decrease damage taken, not sure which game u took that idea from but like in most games in KP it raises the equivalent of hp (endurance) (which you also use for most of your actions).
regarding dealing the same damage i need more information to go on but it might be because of fatigue, or other stat reduction, these are all things you can find in the game itself (looking at the menu, hovering over status effects etc), or it could be the type of attack you are using (str/dex/agi, which abilities do have descriptions of which one they are using).
hopefully that helps a little?
side note while the hours don't really mean much for some of these, i have no idea how you even have anywhere close to that many hours in mgsv tpp, i have less than half and did pretty much everything (and that also includes leaving the game on a few times)
