This is a RuneScape Game Client. I found this on the Runescape downloads page.
info (That was from the page):
-Launch RuneScape directly from your desktop, without all that browser clutter;
-Doesn't require administrator privileges for your PC or Mac;
-The application is open source."
If you are looking this for Mac it can be found here RuneScape - MMORPG - The No.1 Free Online Multiplayer Game
RuneScapeGameClient.zip - Jotti's malware scan
Size of Game Client
Give a thanks please while you are at it!