New Tower: Plasma
Fires a slow-moving blast that damages enemies as they pass through it
Plays very differently from the rest, placement matters more than ever

Gameplay Changes
Manual wave start (no more forced prep timer)
Added perfect wave bonus
Enemies now react more to damage (improved hit feedback)
Visual & UI Improvements
Improved camera framing and zoom for a tighter gameplay view
Map selection now uses real in-game map previews
Added a scrolling message panel for gameplay events
Achievements
Added 9 new achievements:
No leak (Normal / Hard)
250 Plasma kills
New 1000 kill milestones for every tower
