To find the value of S, we can first notice that the pattern of the terms is alternating between positive and negative.

When we expand the terms, we see that:
(-3)^0 = 1
(-3)^1 = -3
(-3)^2 = 9
(-3)^3 = -27

We can see that the pattern is that the sign alternates between positive and negative, and the value is multiplied by 3 each time.

Since we are adding up to 2015 terms, we can see that the pattern will continue until the exponent reaches 2015.

Therefore, the value of S can be calculated as follows:
S = 1 - 3 + 9 - 27 + ... + (-3)^2015

To find the value of S, we can use the formula for the sum of a geometric series:
S = a(1 - r^n)/(1 - r)

Where:
a = 1 (first term)
r = -3 (common ratio)
n = 2015 (number of terms)

Plugging in the values, we get:
S = 1(1 - (-3)^2015)/(1 - (-3))
S = (1 - (-3)^2015)/(1 + 3)
S = (1 - 3^2015)/(4)

Therefore, the value of S is (1 - 3^2015)/4.