Radical Castle is a point-and-click adventure game released for Macintosh in 1986, developed in World Builder and distributed as shareware by Christopher Kent Wigginton.

[2] Players assume the role of the 'Squire', who after mistaking the princess for a serving wench, is given a choice by the King between death and a quest to recover an oracle stolen by a wizard.

The game was distributed on magazine shareware collection disks, Macintosh user group mail-outs, and pre-Internet online services.

[4] MacUser cited Radical Castle as an example of World Builder's "ability to allow authors to design commercial-quality adventure games.

"[2] In 1987, Macworld selected Radical Castle as a runner-up to Deep Angst as the best World Builder game.