Chrono Warfare : Eternal Guardian

P.S If the game might be laggy at first, so after the install is complete, run it for a few seconds then restart. That seems to help. Will run better on higher end devices.

The Bastian of Time is under attack by forces from across time periods, the chrono elder has summoned you, the greatest military mind of all eons to command the Chrono Turrets and wipe out the attacking forces.

A tower defence fps strategy shooter.

2 towers and 2 gates, each of which hold the balance of time.

2 towers, 2 vantage points for the player to hop between.

Killing enemies grants you hours of time. Time is currency. Use it to upgrade each of the towers. Spend it to purchase explosive cans that can be used to blow groups of enemies up.

I have incorporated all 3 themes :

Time Keeps Yawning : Slow time down to blast enemies more accurately with a great hail of bullets. 

Running out of Space : As each gate falls, the enemies spawn closer and you lose a turret. Offensive capability get diminished and the battlefield tightens. How long can you survive?

What a Long Strange Trip It’s Been : Time is behaving erratically, you get pushed to different time periods after every 2nd wave you survive.