Here is a sneak peek into two systems: Skill Tree + Milestones

Skill Tree

As you complete runs, you gain EXP. When you level up, you'll now gain skill points and be able to spend them on a brand new skill tree at the workshop.

The skills have extremely high level caps, and can be upgraded almost infinitely.

In future, the skill tree can be expanded to give you mana regeneration and exciting spells you can cast. Some spells I have ideated are:

1. Repair - MP-50, instantly repair the last X buildings destroyed by the storm
2. Shield - MP-50, instantly add a shield to the nearest building
3. Vehicle - MP-200, summon a vehicle
4. Turbo Boost - MP-50, for 60 seconds, all building production speed x2
5. Pushback - MP-100, push the storm back 50 meters

Milestones

Milestones have been added to each map. Reaching milestones can grant you items, EXP, or skill points directly, the most valuable reward.

Hope you'll like it!