DIY Double Hourglass-like Game Timer for Paintball

I'm very sorry this is so verbose. To get to the actual concept skip down to "The Purpose" section.

First, I'll describe where this idea came from so you can better understand what I'm talking about. Then I'll propose the arduino project.

In World of Warcraft there is an area that has a specific zone that you have to be in for a certain amount of time to gain control of that zone. When you enter the zone a bar with a slider on it shows you how much time you have to be in that zone before you gain ownership of it. Half the bar indicates your faction; the other half indicates the enemy faction. The slider moves at a fixed rate in either direction depending on which faction is occupying the zone (If both factions occupy the zone the slider doesn't move).

As I figure it, the logic behind the time can be explained with 2 hourglasses. Imagine they are on a table in a room. If a member of one team enters the room they can turn their hourglass to begin to gain ownership of the room. If an opposing team member forces that one out they must flip that teams hourglass and wait for it to reset before they can flip their own hourglass…the first team to have their hourglass run out is the winner.

Now for the arduino project. I've drawn out and attached a very basic proof of concept to illustrate what I'm thinking.

The Purpose:
This timer will be set in the middle of the paintball field. Each team will move as quickly as possible to hit their team's button to start the timer. If a player is tagged with paint, they must return to their starting point. If the opposing team is able to hit their button, the timer reverses direction; it does not jump back to zero, it simply reverses direction where ever it was at. So if the red team occupied the zone for 2 and half minutes before the blue team hit their button, the timer would count 7 and a half minutes to sound the horn and end the game (the original time was set for 5 minutes once the button was pressed).

The Logic:
The program would have to provide a menu prompting the user to indicate how much time to set as a starting point. It would then listen for either button 'A' or button 'B' to be pressed. If button 'A' is pressed it will start counting down from the time the user indicated. It would then listen for button 'B' to be pressed or run out of time and sound the signal for 1 or 2 seconds. If button 'B' is pressed, it would reverse the direction of its countdown, adding the time back until it reaches the starting time then would proceed to countdown again listening for button 'A' to be pressed or to run out of time.
In addition, when button 'A' is pressed, the red button, the large digit display would show red numbers. When button 'B' is pressed it would show blue numbers.

Here is a proposed parts list:

-a housing of some kind (strong enough to get dirty)
-a large 4 digit display (2 digits, a colon, 2 more digits)
-a small LCD display
-2 large (4"x4") buttons durable enough to take an impact
-a key pad to enter data (time in minutes/seconds)
-an arduino to provide the functionality
-an air horn or loud buzzer
-a battery of some kind
-the random electronic components required to wire it up
-anything else I forgot to mention here

What do you think, can this be done? I'm looking for guidance on both construction and programming. Thanks for your help and patience.


There is a great video on youtube that has a lot of information that I would be able to use but it's just different enough that it doesn't really help; especially with the programming logic; it is a uni-directional timer that only counts down. The video is called "Countdown Timer With An Arduino - Lets Make It - Episode 42"