Pyramid Scheme
With all the scheme dialects out there, I suppose it was inevitable that a Pyramid Scheme should arise. Created in early 2017 by our very own Conor O'Brien, this 2D esolang does in fact read very much like Scheme!
Length 1
^
This little guy is the start of everything. The tip of a pyramid. Without the caret, there can be no Pyramid Scheme. On its own, though, it's not a valid program; you've gotta rest the pyramidion on something...
Length 3
^
-
There it is. A full pyramid, complete with base and capstone. This 3-byter is the shortest program that will not error; it prints 0 followed by a newline and terminates gracefully. What it's really doing is accessing the default value of the variable-without-a-name; more on variables later, once we have larger pyramids.
Length 4
^
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Exactly as before, but now with a leading blank line! This program does nothing; it is the shortest possible program of the sort. Execution in Pyramid Scheme always begins on the first line. Each pyramidion on that first line is evaluated, and then the results are printed with linefeeds between if nothing has yet been printed. As the first line here is blank, nothing gets evaluated or printed.
Length 5
^^
--
On the other end, here's a program with more than one pyramid at the top. The one on the left will be evaluated first (yielding 0, as in the length-3), followed by that on the right. The results are collected in a list during execution; once all evaluation is complete, since nothing has yet been printed, the results are dumped to stdout:
0
0