In response to the previous comment.

This is the type of application that only runs when placed in the Applications folder. The writer of the previous comment was running it from his Home/Documents/Downloads folder. That's why it wouldn't run. Place it in the Applications folder and it will run just fine.

(Extra tip: Did you know you can create a folder called Applications in your Home folder and it will behave just like the top-level Applications folder?
Or that you can create a folder called GrabBag in either Applications folder that does the same thing?
These tips are from "The NeXT Bible" by Doug Clapp from Brady 1990. A day-one feature of NeXT OS still lives today in Mac OS.)

Works as it says it should work, EXCEPT that unchecking "Enable SleepTight" does not disable it. Once it's on, it's on. Turning it off does not turn it off.