A group of coders decompiled the source code for Sonic the hedgehog and its 1992 sequel to their famous 2013 smartphone ports. This means that these heavily improved versions of the early ’90s Genesis games, developed by Christian whitehead using the same revamped Retro / Star Engine that powers Sonic mania—Can now be easily recompiled for playing on new platforms including PlayStation Vita, Nintendo Switch, and Windows / Mac computers.
It’s a pretty interesting hack / coding achievement in itself. But with a bit of tinkering, the PC versions also allow gamers to scale the game window to any arbitrary resolution, expanding the visible playing field without enlarging the core pixel graphics of games. As you can see from the images and videos included in this article, this change effectively zooms out the in-game standard camera to show huge chunks of one scene at a time, giving players a new and exciting perspective. on these classic titles.
Fill your PC screen with a Sonic the map is not as simple as dragging the corner of the game window. First, you need to grab a legally obtained copy of one of the 2013 Sonic games (which are still available on Google Play and iOS App Store) and extract the “RSDK” file to your computer (this handy video tutorial may come in handy there). From there, you can run the precompiled Windows version and edit the settings file to expand the playing field horizontally with relative ease (you can also change the pixel scale if you want to effectively zoom the camera of the game on a big screen).
Unfortunately, the vertical height of the game remains hard-coded at 240px in this version, which means the game looks like a long thin strip when stretched across the width of a modern PC monitor. To extend the playing field vertically you have to dive into the decompiled source code, change “SCREEN_YSIZE” in the retroengine.hpp, then recompile a fresh new executable (there are some tricky dependencies involved to make this work; many thanks to @CodeNameGamma for his help in my attempts).
The view from a thousand feet
Once things are working out, however, the effect of this “zoom out” view is immediately striking. The standard 32 x 48 pixel Sonic sprite becomes lowercase, Where is Waldo-sque speck on a 2560×1440 monitor (or even smaller if you have a 4K or large screen). The new vantage point allows players to see well beyond the narrow 320×224 screen area they may be used to on the Genesis, allowing them to consider the scale and design of these levels. massive at the same time. Hidden paths and secrets that once passed in a blur become immediately apparent when you can take an ultra-high view of a scene at a glance.
These 2013 mobile ports were originally designed to run at “full screen” resolution on a variety of different smartphones, so the engine handles all of this rescheduling pretty smoothly. Enemies, moving platforms, and animated background elements generally work, even if Sonic is thousands of pixels away in the opposite corner of the screen. The physics of the game still work as expected and everything is rendered with pixel perfect authenticity at 60 fps as well (assuming your machine can handle all of those pixels at those extended resolutions).
Still, there is some weird gameplay and visual artifacts when you try to adapt a game originally designed for 90s standard-definition TVs to modern computer resolutions. This is most evident at the end of many levels, where Sonic can get stuck on a newly obstructed invisible wall and the game hits an endless loop while waiting for it to unfold off the screen. On flat levels, the background tiles and even the level architecture itself can sometimes repeat in a vertical pattern. And the AI for Dr. Robotnik’s boss battle also tends to panic a bit thanks to the new, much bigger playing field.
These issues can be fixed as hackers continue to tinker with the source code and build new versions of these freshly decompiled games. Until then, however, we’ll never watch the classic Sonic the same way again.
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