Balance changes
- Barriers and Walls now require and use a small amount of power.
- Barriers and Walls slowly decay when unpowered, down to 10% of their maximum health.
- Raised cost for Barriers and Walls.
- Walls now require Commander Abilities II research.
- Slightly lowered NX300 damage.

Other enhancements
- Updated Play menu for easier navigation to server browser.

Other fixes
- Fixed missing placement constraints on power relay structures.