Give Bill And Ted The Game this much, it's ambitious. It's ambitious in that special LJN way of the NES days, though. Where presumably some developer went to management with this cool concept for a game drawn up, and the response was "Great, your budget is $50 and here's a couple of gibbons to help with programming." See also Jaws, Friday the 13th, etc. Some neat concepts, but just not executed well at all and seemingly rushed just to get something halfassed out the door.
I say it's "ambitious" because it tries to blend some adventure game elements and an isometric perspective in with the typical generic licensed run-and-jump platformer template of the time. The gameplay decisions here just consistently make no sense whatsoever, though, unless you assume it was shoved out the door too fast and with too little polish.
So the game takes place between the two movies, as some Time Crank Yankers have moved historical dudes and dudettes from one period to another just for a laugh apparently. Bill and Ted have to go clean things up of course, but they have to do it separately for some reason, each with their own time phone booth. So no back-and-forth dialogue exchanges whatsoever, which was really the major appeal of the movies.
You start the game with a phone book packed with historical figures like Socrates, Elvis and Marilyn Monroe ... awesome, which cool time period should we go explore first? Well, as you quickly find out, calling any of their numbers just burns one of your crucial stock of quarters. You have to flip all the way through the book, then back again until you see a different red number blinking under someone's name -- that's the one time period you're allowed to go to, which apparently is in a linear set order that always begins with Rembrandt.
Then you have to navigate the Series of Tubes that represents the space-time continuum. You can just sit still and let this unfold automatically, but you'll need damn near the full 15 quarters the game starts you out with as it costs at least two to move between each set of digits. You can try your luck at shooting over the numbers in order to save your quarters ... but with no real indicator as to which way you'll launch when you press the button, it's really just like gambling at terrible odds and will almost never help.
Once you finally get to one of the game worlds, it kinda feels like moving around in a skateboard game minus the skateboard. The rules about terrain are bizarre, though; you have to stick to walking paths, but you can jump onto the grass, and sometimes when you jump on the grass there are certain zones where you're allowed to walk, but they're totally unmarked and undifferentiated from the zones where you just fall on your ass and have to keep jumping to get out.
There's also no initial explanation as to what you're supposed to be doing, but as it turns out the historical figure is in hiding somewhere in the level, and won't come out until you tempt them with some item they like. How do you find said items? Literally jump and push against random objects like trees and rocks! There are townspeople who sometimes give you a clue as to where objects are hidden, but that system is all moon logic as well. Townspeople who are standing still are generally safe to approach, but the ones walking are like a 50/50 shot they'll just jack one of your coins for touching them ... and then at random sometimes some Chester the Molester version of them will spawn out of nowhere and run at you with arms outstretched, avoid them at all costs or they take you to the pokey of that time period. At minimum that means starting from the beginning of the level again, but if you're out of skeleton keys it's game over.
Unfortunately, even talking to the standing NPCs isn't simple. You have to chat up everybody not just for clues to the important items, but also because they give you coins and keys and replenish your throwing weapons. Sometimes they'll hit you with a dialogue tree though. It would be cool that an early NES game was trying to implement dialogue trees, except they're clumsy and a pain to navigate. They tend to have that Willy Beamish problem of having to guess which answer is the least insulting; guess wrong and you usually either lose a chunk of coins or go straight to jail.
Ultimately, everything about the game is just so tiresome and clunky it isn't worth bothering with. Not excellent by any stretch of the imagination.