Fallout 2 is NOT HARD, in fact it is a relatively easy game. I am playing on HARD + ROUGH difficulty and I don't find the game difficult at all. Why? Because there are a few simple mechanics to exploit which makes it very simple right from the start.
(1) Start with 10 Agility and you will win every fight until people with guns show up. I never take any damage in the Temple, I don't take any damage fighting Golden geckos, I don't take any damage fighting the Rat God. I kill all of these with empty hands, I don't even need a spear and I do not invest any skill points in unarmed combat except for the free training from NPCs at Arroyo and Klamath. It's very simple... Practically nothing in the game has 10 AP. Most have 6, 7 or 8. It takes the enemy 3 AP (min) to attack you. So if you attack him with 3 or 4 AP, then use the remaining 6 or 7 to move away from him, even if he has 8 or 9 AP, by the time he expends 6 or 7 AP to come next to you he no longer has enough AP left to execute an attack -- which costs 3 or 4 AP (min). When I run out of room to back away, I let the enemy come next to me then use all 10 AP to run past him in the other direction ending up (again) 6~7 spaces away from him. Even if my chances to hit is 18% if I can always attack without being hit back, I'll always win! Exploiting this mechanic will make you essentially invincible in the early game.
(2) When you get your first gun(s) the aforementioned still works against anything without ranged attacks. However, on HARD + ROUGH difficulty you'll never win as one man against multiple enemies with firearms. As is the case with reality, when there are 6 enemies armed with guns attacking you when you are alone, you can't win. BUT, if your Agility is 10 and Perception is relatively high 7+ you are going to act first and you'll be more than 10 spaces away when they fire their first shots. Chances are you'll get away before dying because they'll miss a lot at longer ranges.
(3) So how do you engaging humans with guns so you can loot their weapons and get better guns for yourself? Simple. DON'T FIGHT ALONE, period. Join a Caravan, help some gangsters or simply only engage when the bandits are fighting merchants. Apart from that, just run away. You can level up fighting animals that don't shoot back!
(4) Fallout 2 is an old game and I am replaying it today in a self imposed "Ironman" rogue like mode and on HARD + ROUGH. That is I do not save to reload for do-overs. If I make mistakes in actions I live with the consequences. I only save when I am leaving the game. If I die, it's game over, period. If I die I re-create a character and start over from the beginning. It has been two decades and I have forgotten the details and story of the game sufficiently that it is entertaining. Only by doing so is Fallout 2 of meaningful difficulty and challenge.