add guide

README.md

@@ -1,2 +1,13 @@
 # Elemental on CLI 
-Elemental combination game written in C.
+Elemental combination game written in C.
+
+## Single-player
+A single-player example pack is provided as an example in ``combos.txt``. This can be customized by the user, although internal limitations require the combination string to be in alphabetical order.
+
+## Multi-player
+To set up multi-player mode, create a directory ``elem-data`` and create separate directories for each user that plays.
+
+The game can now be played with the following syntax, inside your user directory.
+```sh
+./bin/elem your_username
+```