OverPlay is a Chrome extension developed by NokiNyx that enhances your YouTube viewing experience by providing a chat overlay when watching streams or videos in fullscreen mode. This free extension allows you to read and write chat messages seamlessly without having to exit fullscreen mode.

The chat messages are displayed as semi-transparent text bubbles, with the message input area hidden until you hover over the bottom section of the chat overlay. By default, the overlay is positioned on the left side of the screen but can be easily moved by dragging the handle on the top-left and resized by dragging the handle on the bottom right. It's worth noting that this extension is currently basic in functionality and may undergo updates in the future to improve its features.