I remember spending a good amount of time in the past searching for a plugin that would enable mosaic tiled galleries. I was never able to find anything outside of Jetpack, which, I think, may have required that your images be hosted off-site in order to enable this feature. Having recently disabled Jetpack on my personal blog, I was happy to stumble upon Catch Gallery today. Here's a quick screencast of me initially installing it on my blog. I was pleasantly surprised – didn't even need any configuration to bring those pretty galleries back to my blog. Well done Sakin, Pratik, and Mahesh!