gnu: Add slingshot.

* gnu/packages/games.scm (slingshot): New variable.

gnu/packages/games.scm

@@ -6118,3 +6118,30 @@ to download and install them in @file{$HOME/.stepmania-X.Y/Songs} directory.")
     (home-page "https://www.stepmania.com")
     (license license:expat)))
 
+
+(define-public slingshot
+  (package
+    (name "slingshot")
+    (version "0.9")
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/ryanakca/slingshot.git")
+             (commit version)))
+       (file-name (git-file-name name version))
+       (sha256
+        (base32
+         "19m8b6nsi786bc6gmkp185mwri3r5y249gjmqd5qsc23nnfhgrs1"))))
+    (build-system python-build-system)
+    (arguments
+     `(#:python ,python-2))
+    (inputs
+     `(("python-pygame" ,python2-pygame)))
+    (home-page "https://github.com/ryanakca/slingshot")
+    (synopsis "Simple 2D shooting strategy game set in space")
+    (description "Slingshot is a two-dimensional strategy game where two
+players attempt to shoot one another through a section of space populated by
+planets.  The main feature of the game is that the shots, once fired, are
+affected by the gravity of the planets.")
+    (license license:gpl2+)))