Sandboxie-Plus is a fork of Sandboxie designed to address various problems as well as adding improved functionality.
Sandboxie allows you to run programs in an isolated and protected space. This protected space will prevent any permanent changes being made to other programs and data to your computer, allowing you to test, play, and utilize them without fear of harming your machine.
Sandboxie-Plus fixes many known issues and security holes of the last official Sandboxie release, adds new functionality, most notably a new Qt-based UI SandMan.exe that is far more advanced than the old MFC based SbieCtrl.exe UI. The security fixes are essential as they effectively close privilege escalation and sandbox escape issues present in the last 5.33.6 official build.
For users preferring the old lightweight UI, the SbieCtrl.exe, it is still provided and being updated.
Sandboxie-Plus will have many more features to come. The author's vision is to develop Sandboxie-Plus into a full-featured app virtualization tool like Altiris (later Symantec) Software Virtualization Solutions, which is now discontinued. A detailed process analysis functionality will be added, and an API call log that is already included, and more will come helping in malware analysis and similar tasks.