There used to be a periodical column in the 80's called Gold Mine that contained tips and cheats for Commodore 64 computer games. The column appeared in Commodore Magazine (starting officially from the June 1988 issue) and later (from the December 1989 issue) continued in RUN magazine. A compilation of this sort of gold makes up the bulk of the book titled Lou Sander's Gold Mine: Game Tips for Commodore Users by Louis F. Sander (1990), ISBN 0830683232 / 0830633235. This book is available from the Hennepin County Library in Minneapolis (LCC: GV1469.15 .S26 1990) where you can also find some of those original magazines. Interestingly, the very same issue of RUN magazine that continued the Gold Mine column also contained an advertisement for this “new” book itself, such that you're unlikely to find any of the subsequent tips in the book (probably just the ones from Commodore Magazine plus some previously unpublished ones).
In this book you can discover how to improve your game-play strategy in retro games like Transformers and Commando, find tricks for Popeye, learn how to become indestructible in Wizball, get unlimited cars in Breakthru, warp between levels in Crystal Castles, get infinite lives in Bomb Jack, and much more. Some of these tricks involve pressing your favorite reset button, entering POKE and SYS commands, renaming or modifying files on disk, and so on, although many are just simple hints being described.
Several gold nuggets were submitted by people all over Minnesota (nobody from Minneapolis though?!), such as by Adam Larson in Anoka, Robert Rovinsky and Dave Newberry in Duluth, Mike Barber in Park Rapids and Chad Paulson in Villard. Then there are even contributions by readers from up north in Winnipeg (Canada), where I also lived for a few years, such as by Colin Adams, Steve Rohatynsky, Jonathan Stapinsky and Nelson Yung.
In the last chapter one can find contact info of many Commodore software publishers (most definitely outdated by now). One of these publishers I discovered was located in St. Paul, Minnesota, called Box Office Software Inc. (or sometimes just Box Office Inc. for short), in that beautiful historic Pioneer Press Building on 336 Robert Street North. They published the game High Rollers, circa 1988, and I believe also Alf's First Adventure. Richard Hansen apparently worked as a programmer on both those games, while Robert P. Devine seems to have been the principal on record for that computer software publishing company. Box Office Software also published a Commodore version of The California Raisins game.
The Donutron is an indie arcade cabinet and features games that are made locally in the Twin Cities area. It can be seen today at Maker Faire MSP, presented by Zachary Johnson (Zachstronaut) and Victor Thompson (Caper Academy). Wouldn't it be nice if The Donutron could also showcase this bit of local Commodore game history?
In addition to Lou Sander's Gold Mine book, other Commodore 64 and Commodore 128 literature can also be found at a Hennepin County Library near you. See this post for a complete list.