Dubby said:
1) Conventional map-travel with random encounters, including special encounters
2) Robust dialogue limitations based on the player's intelligence score
3) Improving and expanding the main quest
4) The addition of many more weapons
5) Ability to upgrade weapons with schematics, parts & a workbench
6) Improving the quality of textures and graphics
7) Improving the musical repitoire of the GNR radio station
8) Enhancing the combat AI for better targeting & real time decision making
9) Follower UI allowing the player to modify the follower's combat behavior
10) Among other things - finishing traits & perks!
11) Overhauling combat damage & defense to take into account armor penetration among other things
12) Overhauling projectile ballistics to be realistic, and take into account effects like muzzle velocity, wind speed, ricochet, and more
13) Adding more targetable regions to VATs for all weapons, especially Melee & Unarmed
14) Strength requirements for all weapons, for the player & the AI
15) Weapons that can use different types of ammunition for different effects
16) Improving the range of statistics, such as Luck affecting random encounters & loot
17) Improving the range of various skills, such as Science
18) Implementing the Outdoorsman, Gambling, Throwing, Doctor, & Traps skills
19) Revamping addictions & withdrawal behaviors
20) Adding unique/original content
21) Revamping how the player needs to handle crippled injuries
22) Combat Reflexes for the player, alters the flow of time based on what's happening
Overall a great although ambitious list. I might as well throw a few of my own suggestions into the mix. Some have been mentioned before but I figure I might as well put them up again.
23) Fix weights - Ammunition is not weightless, A full soda and an empty soda do not weigh the same, etc.
24) Factions - Every action/interaction can change how each group views you and your group(followers). Generally this would break down into 5 categories:Shoot-on-site, Unfriendly, Neutral, Friendly, One of the Group
25) Clothing matters - Having a weapon out and having a rival/evil/unwelcome armor on means getting shot at until you are close enough that you can be identified such as wearing Enclave Armor near the BoS. This would also open up the option of infiltrating camps and groups.
26) Change Little Lamplight and Big Town to normal towns - Lord of the flies for 200 years? I doubt it.
27) No invulnerable characters - Will require fleshing out new branches on the plot tree to allow for the death of certain characters.