It sure wasn't this easy back in the '90s. Three minutes after downloading GB Studio, I'm making a Game Boy game—from a drop-down I tell an NPC to walk in a random direction, and set the small sprite of a cat to say Bark! instead of Meow! because I'm a true rebel. I'm just messing with the example game that ships with GB Studio, a free tool for designing mini 2D games without any coding, and it's pretty wild that I can click "Export ROM" and spit out a file that will work on an actual Game Boy.
GB Studio is impressively straightforward. As a teen I spent months dabbling with RPG Maker 2000, which could do more than GB Studio but was also a mess of confusing menus. RPG Maker's later versions have grown far more powerful, but if you're serious about it you'll probably end up wanting to do some coding, or have to master a million menus. The natural limitations of the Game Boy, on the other hand, make it a perfect candidate for a visual editor.
In GB Studio it's super easy to click on an object and link it to a sprite sheet, set a few basic behaviors like walking or rotating, write some text that triggers when you interact with it, and so on. Scene switches from one location to another are intuitively visualized. Graphics are easy to import. You couldn't build something as deep as Pokemon in this thing, but a basic little adventure game? Hell yeah.
You can spit out a game as a Game Boy Rom or save it as a web app. It'll automatically create an HTML5 version of your game that works on phones or easily uploaded to Itch.io like this one by GB Studio's creator Chris Maltby.
Hopefully there's more to come in the future. As Maltby posted on Reddit, "This version is mostly for creating simple adventure games with no combat, there's the ability to make decision trees in the dialogue, you could do fetch quests and you can do block puzzles and things like that too. I wanted to get this version released while I have a think now the best way to expand it in the future :-) No color support just yet either, keeping it simple for now!"
Throw some basic combat features in there, and we'll be most of the way to making infinite Zelda: Link's Awakening knock-offs.
If you make a Game Boy game, share it!