A post on FragWorld.Org offers what they call "The First Person Shooter Community Manifesto," a list of desired features for future first-person shooter games compiled thanks to a meeting of members of the community (thanks joao). They have a recording of the audio from that meeting for download, and the lists of their essential and suggested FPS features follows.

These are the ESSENTIAL things we HAVE to have in a FPS Shooter

1. Dedicated Servers - for performance and countless other reasons. Co-op game modes and games should also have dedicated servers
2. Mod Tools - This will save you development costs by giving your customers new content and no cost to you and give you great ideas for the next version of your game. Whatever you can't put in the game we can put it in for you. Just give us the tools please.
3. As much server side control and options available (the ability to control maps, gametypes, weapons, special abilities, filter language, kick hackers etc). For private matches in particular it is important to have features either built into the game or via 3rd party mods to ensure a level playing field for all players and the ability to create different rulesets.
4. LAN Capability - So people at Lan Parties, Tournaments, College Dorms, Gaming Centers and their friends houses can enjoy face to face competition without requiring each PC to have internet capability
5. Stat Tracking - API, Log file or do it yourself we need to be able to see how we and others are doing.
6. A Capable Server Browser that shows all the options mentioned in #4 filterable by ping, server location, gametype, map and whose data can refresh in real time.
7. A Section in the Game's Official Forums for verified server owners so they may have constructive dialogue with each other and with the game developer.
8. In Game Recording - Machinima, Commentaries, Frag Videos, Tutorials, and other Video Broadcasting is free advertising and marketing of your game. It helps us run cheat free events the promote your product. Having a capable spectate mode also facilitates this as well.
9. Anti-Cheat - Definitely have a strong Anti-Cheat out of the box and work with the community and Anti Cheat Companies in staying up to date with the latest Anti-Cheating Methods such as the ability to force settings in private matches and detect adjustments to exe files
10. Allow Config files to be editable in game via console or interface

These are SUGGESTIONS we have to make a great FPS Game

1. Map Editor - Creates content for your customers and no development cost to you.
2. Front End Administration of Servers - A pulldown that allows you to kick and perform server admin functions while in game.
3. Server Side Demo Recording
4. Stat Tracking by Server
5. The ability for server admins to flag suspicious players which instructs the server to record/screenshot them or conduct extra anticheat detection on them.
6. Social Networking integration - See achievements, stats etc on facebook or web widgets/API so communities can post on their websites
7. Clan level achievements/leveling/features similar to what guilds have in MMOs
8. Invisible spectating in "public" servers for server admins
9. Special Beginner Servers for people new to the game
10. The ability to assign a trackable skill level to a player (ELO) and see the average skill level of the players in a server via the server browser
11. A Tutorial on how to use the server browser
12. To expand #3 in essentials we desire certain features for fair competitive play
    1. The ability for all players to start at the same time
    2. The ability to see a clear end of game scoreboard and leaderboard with stats and score at the end of each round and match
    3. The ability to limit and control weapons and special abilities (this allows for exclusion of undesirable weapons and abilities and allows for sniper only or infantry only type gameplay)
13. Spectating/Broadcasting - In addition to in game demo recording allow for free and follow spectating to promote the game via live broadcasting and commentary which can be done via shoutcast, ustream , Justin TV etc..)