Press the button in the bottom right-hand corner to swap between the up/down and left/right engines. The engine supports arrow keys (up/down or left/right depending on which version of the engine you choose), touch/mouse (touchpoints shown in project), and the space bar which only supports going forward. To use, just backpack the sprite you wish to use and add it to your project, then add it to your project and replace the costume with your own. Make sure to provide credit in your project for the slide to my main account, @da-ta.
In 2020, I made the 1.0 version of my slide engine, and in 2021, I released it for free for anyone to use. Since then, I've used it myself in most of my projects. But recently I felt it would be good to improve it to make it faster and simpler, and this is the result! Please make sure to provide credit if you use this to my main account @da-ta! You can also ask any questions in the comments below. 1.0 version of the slide engine: https://scratch.mit.edu/projects/576339508/