Added:

Each tower now displays the number of improvement points spent on characteristics.

Map number 23 is finally available.
Prepare yourself to deal with even more enemies!

Improvement & balancing:

Reduced player level gains.
Improved shuttle damage immunity (from 5% to 7%).
Slowed enemies no longer benefit from the bonus of a speed path.
Improved the damage of the fragmentation missile tower, but reduced its firing speed (general DPS unchanged).