Narwyn/Game-Launcher ? reverse-engineered prompt

Build me a customizable game launcher app that looks and feels like a real desktop launcher, with a clean interface I can style easily using HTML and CSS. It should check the game files on the user’s computer, compare their SHA 256 hashes with a remote list from a server, and then download, replace, or add any files that are missing or out of date. I also want the launcher itself to be able to update automatically.

Please make it easy to swap themes, like normal, Halloween, Christmas, and other event skins, so the whole launcher can change its look without rebuilding everything. Use a simple Electron based desktop app structure, and keep the example polished like a launcher for an online game. If you need to look up current docs online, go ahead.