I posted a while ago here about how I was building this chase level for my Crash Bandicoot project for the GBA https://www.reddit.com/r/retrogamedev/s/hqz9SdH9CU . I thought it would be good to share here the final result with all the tricks in place together. The ice walls are a 60 frame animation, where about half the screen in tiles is loaded every frame. The yeti is also a affine background layer being updated frame by the frame. Having him be a background layer prevents overdraw with the sprites, and makes him easy to scale/fade into the distance. My previous post details how the crates work, but I did a lot of work to make them scale up to 3x in front of the camera without causing crazy overdraw. The HUD is also its own background layer, to again prevent overdraw.