The BIFROST* Engine is a multicolour 8×1 graphics engine written by Einar Saukas, featuring sample tiles by Dave Hughes, supporting a multicolour square area of 18 character rows by 18 character columns. It's open source and royalty-free (even for commercial programs). Further details can be found in this link. The latest version is available for download here.
It natively supports all standard Spectrum models (48K, 128K, +2, +2A, +2B, +3). Moreover, engine logos can be obtained here.
List of released games using the BIFROST* Engine:
- Knights & Demons DX by Baron Ashler, Einar Saukas, Craig Stevenson
List of games currently under development: