Drag the blocks! On some blocks, such as 'set var to', 'var', and '...', you can input data directly - for the 'var' blocks the data is used as the name of the variable, and '...' simply returns what you put in it like a text box. For every instruction, the arguments should come after the instruction. For example, "add 3 2". As there are many, many blocks, use the up and down arrows to scroll through the code or the block list (depends on where your mouse is). You can also use the recently added category system.
This is a redone version of sTac. Blocks can now have variable sizes, all information about the types of blocks are handled via lists to reduce repetition, and the text input to the input and comment blocks is separated from the block names themselves. The example program demonstrates some of the basic control structures within the language. StackBlox has first-class continuations and completely manipulable control flow.
