apologies this may be a long post, (even knowing that my rantings will have little effect on any outcome)
in no order:
Factions that are notable and each can be joined, destroyed or otherwise interacted with. to such extent they'd each have distinct storyline functions.
Scarce and hard-done communities, In FO3 (as has been mentioned) everything was just peachy wherever you went. lets see some suffering in the wasteland I enjoyed FO2 as I visited different locations and took in what it had to offer, for example: The den a very basic place really, but those that weren't druggies had their own problems, the slavers offered a variety of different quest options, even the 'sub-quests' were appropriately fun and interesting (re-fuel the still anyone ?), and when I found vault city I was actually taken aback at just how nice the place was... then I began finding out about what it means to be a part of vault city. again, with soo many quest options from jsut this one location.
weapon variety, Fallout Tactics had this right (and with mods FO3 has some good user created content) I don't much care that one guy has an FN FAL and another has an AK and they do damn near the same damage.. I do enjoy the aspect of 'these are the only weapons we could get hold of' rather than the absolute gun-frenxy-fest that is FO3. In FO2 I can remember how painfully long I had to make my first pistol / sawnoff last, how desperate the early game was literally preying that I find an extra few shells soon knowing that one bad encounter and i was dust if I couldn't. It also gave me more respect and sense of accomplishment when I finally got some combat armour and an automatic shotgun, I felt like a god!
As someone else mentioned community interaction, (sorry to keep going back to it but...) FO2 was amazing for the level of interaction between the communities, there is probably a better example, but i still remember travelling back and forth sorting out the raider attacks on Vault city, re: NCR, re: New Reno.
rather than a blanket, good bad karma, personal relationship levels in some fashion, let each notable person or faction or location have their own opinion of your player character dependant on your actions and interactions.
S.P.E.C.I.A.L stats that mean something, as i proved FO3 was playable even with SPECIAL stats set at 1. in any other role play EVER if your stats were all baseline, you'd not get far/die rather quickly.
Fallout style PERKS/TRAITS, please see examples: Fallout, Fallout 2, Fallout: Tactics. Some old ones, some new ones, but it must be done in the way it was in the classic games.
Less stuff in the wastes!!!! how many '
small burned books' (that are may I add 200+ years old ...?? ) are there in the capitol wasteland? seriously, there was a NUCLEAR WAR.... and 200 years of time passed, there is no chance I'm going to find a fucking '
finance clipboard' in some long lost bunker / house / whatever
Weapons that don't go from condition 100% to condition 10% just by firing a few clips of bullets, I realise these are old guns, but if a gun is said to be in 100% condition is it not assumed its had good maintenance etc, and isn't likely to be falling apart in the near future?
less go to X, collect Y missions... (or as I like to call them, Fallout 3 from start to finish) sure it's an RPG and there isn't HUGE scope for twisting branching mission lines, but heck. This kind of game gets boring. see evidence, Fallout 3.
More complex melee combat, see also: Fallout 1/2 -- punch, haymaker, quick jab etc etc... ok, it was graphically limited, but i'm not stickler for that, I loved having ninja style fistycuff fights in the classic games. its not like a modern computer cant handle the idea!
Some of that classic humour! bridge guardian anyone?! ok, most of the classic games humour was lifted from other material, but lets face it, Monty python ROCKS!
Fun Easter egg's I miss suddenly coming across something completely irrelevant, but highly amusing!
I'm a huge fan of the pnp role-play for fallout (heavily based on Fallout 2) it has a LOT to offer but mostly it adds math surrounding a lot of things like
to hit chance, based on lighting / conditions etc, movement, drug effects and more. Basically, I'd like to see MORE role-play maths in the game, I'm an old hand Role player, +1, 12% these are my bread and cheese NUMBERS are what make a role play a role playing game, sure hide them away if you must, but I for one enjoy all the numbers involved. (and thus have a massive hate of the FPS element of FO3)
I'd want to see armour re-done back to the classic style, so that armours have differing defensive benefits compared to the damage being done. Also, Armour values, Damage thresholds etc...
example:<blockquote>
Fallout 2 power armour stats:
Power Armor
Normal threshold 12 hp
Normal resist 40%
Explosion 20 hp
Explosion resist 50%
Laser threshold 18 hp
Laser resist 80%
Plasma threshold 10 hp
Plasma reisst 40%
Fire threshold 12 hp
Fire resist 60%
Armour Value 25
Fallout 3 stats:
Damage resist 40
</blockquote>
To me the complexity makes each type of armour a tactical choice. and on the same level I could say the same about ammo types, (ball, FMJ, Solid shell, scatter shell EMP shell etc...)
As for the 'standard' BOS, enclave, Muties thing.. meh i enjoyed meeting the Reavers in tactics, heck.. I loved the over zealous 'robot' faction with their somewhat erroneous kill everything orders. so yes, lets see some other main faction as the plot main...
injuries: these MUST be handles like in tactics, Ie, stimpacks become ineffective if OD'd become bandaged if healed to much limbs that stop working and have a rather painfully big impact on your character until it gets seen to, ( I recall having to walk VERY slowly back through one of the tactics missions due to everyone being bandaged and having broken legs! sure my team had survived, but oh boy.. I paid for it!)
probably more, but the phone has rung.. so I'll post this for now.