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 ## Overview
 
-A single-player asymmetric game inspired by DOTA's wave/tower structure, combined with a Factorio-style factory builder. The player builds a factory on an asteroid to supply shipyards that produce autonomous combat ships. Those ships fight off endless enemy waves advancing from the right. Defeating enemies occasionally yields artifacts, which are used to upgrade the HQ; the goal is to upgrade the HQ enough to launch it into space, winning the game. Elapsed time is always displayed.
+A single-player asymmetric game inspired by DOTA's wave/tower structure, combined with a Factorio-style factory builder. The player builds a factory on an asteroid to supply shipyards that produce autonomous combat ships. Those ships fight off enemy waves advancing from the right, with tougher boss waves arriving periodically. Pushing into enemy territory and destroying their defence stations occasionally yields artifacts, which are used to upgrade the HQ; the goal is to upgrade the HQ enough to launch it into space, winning the game.
 
 ## Setting & Visuals
 
@@ -62,14 +62,13 @@ Two sources feed the same production tree:
 
 - Waves consist of a single enemy ship type whose stats scale with difficulty.
 - Waves spawn over several seconds; a gap follows before the next wave begins spawning. The previous wave may still be approaching or fighting during the gap.
-- Difficulty scales multiplicatively from two sources:
-  - **Time scaling** — enemy strength increases gradually over elapsed time.
-  - **Push scaling** — destroying a set of enemy defence stations multiplies enemy strength by a configurable factor. The replacement stations are scaled by the same factor.
+- A tougher **boss wave** spawns periodically on its own countdown, on top of normal waves.
+- Enemy strength increases gradually over time and with each boss wave that occurs.
 
 ## Push Mechanic
 
-- The player is not forced to push; purely defensive play is valid.
-- Destroying enemy defence stations applies the push scaling multiplier to all future waves, extends the scrollable area, and places a new (stronger) set of stations at the new boundary.
+- The player must push — destroying enemy defence stations is the only way to earn artifacts, which are required to win.
+- Destroying a set of enemy defence stations advances the boss countdown (bringing the next, stronger boss wave sooner), extends the scrollable area, and places a new (stronger) set of stations at the new boundary.
 - Destroyed enemy defence stations drop either a ship/module schematic or, occasionally, an artifact.
 
 ## Win Condition