Update 'README.md'

README.md

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 # SpaceCollector
 
-A simple game made as a hobby.
-Use the mouse to control the starship and collect the gems.
-The faster you collect them the better.
-
-Needs pygame (2.1.2) to run.
-
+A simple game made as a hobby.
+Use the mouse to control the starship and collect the gems.
+The faster you collect them the better.
+
+Needs pygame (2.1.2) to run.
+
+## Usage
+```
+python3 main.py <level.svg>
+```
+
+## Controls
+
+- Mouse controls the ship's heading.
+- Left-click accelerates the ship.
+- Right-click stops the ship.