Repeatedly Scrolling (looping) a background graphic would be a creative way to achieve that effect, so, good suggestion. There ARE other ways to get a constant moving background in Roll20! Mainly "GIF" animations, which I believe Roll20 actually converts to some other format. There are some Marketplace products that have this & demonstrates it well: Examples, <a href="https://marketplace.roll20.net/browse/gameaddon/12585/desert-worm" rel="nofollow">https://marketplace.roll20.net/browse/gameaddon/12585/desert-worm</a> <a href="https://marketplace.roll20.net/browse/set/3894/animated-environment" rel="nofollow">https://marketplace.roll20.net/browse/set/3894/animated-environment</a>