When Charles Doty developed the first homebrew CD-i game 'Frog Feast' in 2006, he also experimented with other homebrew ideas by porting various ideas on CD-i, including Connaone (search the blog for more info) and a demo with the Mode 7 effect. These were actually the real first CD-i homebrew efforts,as Frog Feast in principle was a port: Frog Feast was converted to CD-i instead of being developed from scratch for the CD-i.
It was promising that the Mode 7 effect (known from SNES like Super Mario Kart) was also possible, in principle, on CD-i. A strict definition of Mode-7 is a simple texture mapping graphics mode that allows a background layer to be rotated and scaled. By modifying the scaling and positioning of the layer on a scanline-by-scanline basis a simple perspective effect can be applied, transforming the layer into a 2D horizontal texture-mapped plane that trades height for depth. In short it looks 3-Dimensional!
Realtime 3D graphics are tricky on CD-i due to the technical limitations, although Philips performed it really well with the release of Atlantis: The last Resort and Ram Raid on CD-i (both First Person Shooters). But that is different from Mode 7, which has never been explored on CD-i anywhere else.
In 2008, the CD-i homebrew expect Charles Doty succeeded to bring the Mode 7 effect to CD-i and there were plans if this could work in a new CD-i homebrew effect. In short one of the most fascinating efforts in the world of CD-i homebrew! After 14 years, the demo was all that we saw from it, but who knows who dares to pick it up and create another CD-i homebrew game with this!
CD-i member Mr Burns captured the demo running on Mame 0.239 as well, showing the technical limitations of both Mame and CD-i, but still shows the potential of this!
[Thanks, Mr Burns (capturing), Charles Doty (developer)]