$ $

$_$ (pronounced sus) is an esolang by Cortex where strings of a certain character are commands. It was named after the first two characters added, _ and $. Newlines are optional.
A new, 1.5-dimensional (you'll see what that is when I finish the new version) version of $_$, Sus++ is currently being worked on. This page describes the old version. Sus++ will most likely be finished by January 20th. If it is, in fact, finished, click here. (nevermind)
== Constants ==
Name	Default value
s 	Empty string. See _ and $
== Commands ==
In this table, N represents the number of characters. (for the call ____________, N would equal 12) 
Character	What it does 	Category
_ 	Append the character with the ASCII value N to s. 	I/O
- 	Like _, but prepend the character to s instead. 	I/O
$ 	Print the value of s, and reset it to an empty string if N is odd. 	I/O
& 	Separate calls of the same character. 	Control
@ 	Create label N. 	Labels
! 	Assign the most recently created label to the Nth character call. 	Labels
# 	Go to label N. 	Labels
. 	Stop executing. 	Control
% 	Begin or end a comment. 	Control
? 	Ask the user for input and append it to s. 	I/O
+ 	Append the source of the (N-1)th call in the program to s. If N is 1, the entire source code is stored in s.	I/O
1 	Begin defining a new miniprogram N. 	Miniprograms
2 	Stop defining miniprogram N. 	Miniprograms
3 	Add the Nth character in this list to the miniprogram. Followed by a 4 call. 	Miniprograms
4 	Determines N for the character added in the previous 3 call as the N of this 4 call. 	Miniprograms
5 	Run miniprogram N. 	Miniprograms
z 	Wait N seconds. 	Control
; 	Print the lyrics to All Star by Smash Mouth N times. 	I/O
* 	Interpret s as source code. Inspired by InterpretMe 	I/O
== Commands by User:Yayimhere ==
Character	What it does 	Category
< 	add character at index N to s 	I/O
` 	add everything before this command to s	 I/O
^ 	append s to program N times 	self modification
== Examples ==
=== Hello, World! ===
________________________________________________________________________&_____________________________________________________________________________________________________&____________________________________________________________________________________________________________&____________________________________________________________________________________________________________&_______________________________________________________________________________________________________________&____________________________________________&________________________________&_______________________________________________________________________________________&_______________________________________________________________________________________________________________&__________________________________________________________________________________________________________________&____________________________________________________________________________________________________________&____________________________________________________________________________________________________&_________________________________$.
=== Cat program ===
?$.
=== Cheating Quine ===
+$. % this gets the entire source code, making it a cheating quine
=== Skip the first . call and become a cat program ===
@!!!!!#.?$.
=== Define a miniprogram containing the cat program, and run it ===
133333333343343333333425
=== Self-interpreter ===
?*.
== Implementations ==
An interpreter has been implemented in perl by Sxakalo. You can check it out here 
Category:Languages
Category:Unknown computational class
Category:2019
Category:Implemented
Category:Pattern-based
Category:Low-level