Here are a couple more helpful game design related sites I've found!
Seamless texture check lets you quickly see how well a texture you made tiles. You can just and drop your texture file (as long as it's a png or the like) onto the site page. You can also adjust the scale to see how it looks at different distances/resolutions!
One warning for this one - if you use firefox's "dark reader" addon, you'll have to disable when using this site as the addon breaks it.
Mixamo is a site where you can get free animations for your 3d characters! I haven't used it much myself but it looks like it could be a valuable resource for folks having trouble with making their character animations. One downside is that they do force you to make an account.