HD monsters for Marathon 2 / Infinity. These were generated with Topaz Gigapixel AI upscaling using Art settings, with some automatic processing to correct colors and smooth the edges of the sprites. The art style upscales have less detail than the other gigapixel plugin, but this is typically a good thing, as the extra "detail" in the other plugin was controversial. If you like some monsters from the other plugin better, it should be easy to mix-and-match monster collections, by copying the numbered folders from one plugin to another. For reference, the other plugin can be found here: http://simplici7y.com/items/marathon-infinity-upscaled-monsters.
There were some manual edits done to the fighter shapes to keep their staves/glow maps consistent between frames. The inconsistencies were obvious with the higher definition monsters, so thanks to Aaron for cleaning up the originals.