It is a graphics card in the sense of the "ReTargetable Graphics" (RTG) system. I ship drivers for the Picasso96 API (which also emulates the competing CyberGraphX API). All OS friendly Workbench/Intuition GUIs can then be used on a high resolution (up to 1280x720@60hz, 1920x1080@30hz) and color depths of 8 (Palette), 16 or 32 bit. A bunch of open source games like Doom, Abuse, ScummVM have been ported as system friendly applications, too, so these run fine. Old games that bang the hardware still go through the custom chipset of the Amiga and are output through the 15khz RGB connector, not via my card. But I'm currently working on an expansion that scan-doubles and upscales the classic video output, too.
(Edit:) On the hardware side, I implemented the Zorro bus protocol in the FPGA (in Verilog) and hooked it up to a SDRAM controller/arbitrator and DVI/HDMI encoder. There is also a simple blitter in the code.
Are you maybe thinking about adding more things on this one card? Ethernet, USB, memory (e.g. 1GB by default)...
Maybe even emulation of a faster CPU in FPGA (a'la the Vampire for A600).. though, it'd probably use the CPU slot instead of Z2/Z3.
Also, is it possible to hijack the function of the OCS/ECS/AGA directly via the Zorro slots (proxying the native output gfx output, e.g. with games), or maybe it'd require some kind of hardware bridge between the gfx chipset and your card?
(Edit:) On the hardware side, I implemented the Zorro bus protocol in the FPGA (in Verilog) and hooked it up to a SDRAM controller/arbitrator and DVI/HDMI encoder. There is also a simple blitter in the code.