Pretty much agree except, depending on the game Profiles can be a good thing. I had whole families playing XMas Bonus and the husband/Wife/Kids wanted different profiles.
Also I had an option to reduce "snowflakes", particle effects in other words. Admittedly most people would never use this but those with slower machines would get less slowdowns. Alternatively the CPU speed could be measured on bootup and particle effects adjusted accordingly.
Some stuff I put in Xmas Bonus was probably not essential but I thought it was cool (list excludes stuff already mentioned in your post):
- Boss Key (auto minimise when pressed, even from full-screen mode)
- Pause game and stop music when minimised (seems obvious but I've seen plenty that don't).
- Test that alt+tab reloads any corrupted VRAM on ALL screens. Many games crash when I test this on obscure screens.
- When in windowed mode have a close button (X in top right corner), some games don't! Also be able to close it when minimised by right clicking it on task bar and sating close.
- When in windowed mode, make sure left Alt doesn't bring up system menu (or nothing) and pause game.
- windowed mode in 800x600 was actually slightly smaller so that people with 800x600 desktops could see the title bar and the whole game screen, e.g. the bottom wasn't obscured by the Task Bar. This was actually horrid to program as every screen had to be able to position things dynamically depending on the screen size. I won't do this again.
- Same options appear in-game (inc. full screen etc) as on the main menu.
- Ability to select a starting level.
- When game over appears because the user failed to complete level, you can just click Restart Level with a score penalty.
- Restart Level on the options menu. Could be used for cheating I guess except it reduced score.
- Splash-screen/loading bar so they know something is happening.
- fades between screens including music fades.
- not having multiple of same sound effect playing at once at full volume, too noisy!
- mouse cursor with shadow blended with background.
- menus and logos had edges anti-aliased with backgrounds
- didn't use really horridly compressed jpgs.
- download was ~5Mb
- feedback on menus e.g. brighter as cursor goes over and click noise when clicked.
- ability to show instructions each game or turn them off. Ability to view them on an ad-hoc basis via options.
- options saved in ini file so they are restored each time. Plus ini file had some extra settings for video compatibility like a 16-bit colour mode instead of 32-bit and a different way to handle VWait. Probably noone ever used them though ;-)
- Icon on main Title bar same as game icon.
- Installer to have option for user to specify path, icon on desktop, quicklaunch icon etc. Also uninstall option.
- Credits? Mine were in the readme.txt file that noone reads, would have been nicer in game.
I didn't have anything to stop multiple instances loading at onces, that would have been good.
OK that'll do for now, there were loads of other things I did too. At the end of the day, if you get it right the user will never notice! If you get it wrong, they'll go "what hell is that" or "that's rubbish".
There that's my trade secrets, maybe I shouldn't have told you all! ;-)