I'll take a stab.
The Startup-sequence is simple a script and can be seen executing in the first cli. It calls another script: the User-startup (where your customizations should be). I've never done this, but, I don't see why you can't create a branch in the User-startup that asks if you intend to game or surf. Then, you a write a Game-startup script and a Surf-startup script, each initializing the desired environment, and save them to S:. Depending on user input when booting, the corresponding sub script would be executed. The user-startup could wait for 20 seconds for user input and then default to one or the other (depending on what you do most).
It would be a simple matter to reboot anytime you want to change from 1 environment to the other.
Do you have the AmigaDOS manual that came with your Amiga?
