What rules change when you're soloing? If a player plopped down a character sheet all maxed out

What rules change when you're soloing? If a player plopped down a character sheet all maxed out
18 all the way down
Tenth level fighter magic user thief and bard
You might balk at and reject it. Perhaps you fear such power would be abused.
You can trust yourself.
The oracle is there to help you choose among your various awesome ideas. At least two.
Combat can be more dynamic than sword blows and lasers. Characters can perform daring escapes Jackie chan style, or duel all over the scenery. Brawl like WWF.
You could do that with the right kind of player but you could be that kind of player provided you had the rapport with your imagination the keep the ball rolling.