Initial commit: OpenRA game engine

Fork from OpenRA/OpenRA with one-click launch script (start-ra.cmd)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

mods/ra/maps/a-nuclear-winter/rules.yaml

@@ -0,0 +1,14 @@
+World:
+	WeatherOverlay:
+		ChangingWindLevel: true
+		InstantWindChanges: false
+		UseSquares: true
+		ParticleSize: 2, 3
+		ScatterDirection: -1, 1
+		ParticleColors: ECECEC, E4E4E4, D0D0D0, BCBCBC
+		LineTailAlphaValue: 0
+	TintPostProcessEffect:
+		Red: 0.88
+		Green: 0.93
+		Blue: 1.06
+		Ambient: 1.09