We determine the consistency strength of determinacy for projective games of length $\omega^2$. Our main theorem is that $\boldsymbol\Pi^1_{n+1}$-determinacy for games of length $\omega^2$ implies the existence of a model of set theory with $\omega + n$ Woodin cardinals. In a first step, we show that this hypothesis implies that there is a countable set of reals $A$ such that $M_n(A)$, the canonical inner model for $n$ Woodin cardinals constructed over $A$, satisfies $A = \mathbb{R}$ and the Axiom of Determinacy. Then we argue how to obtain a model with $\omega + n$ Woodin cardinal from this.

We also show how the proof can be adapted to investigate the consistency strength of determinacy for games of length $\omega^2$ with payoff in $\Game^{\mathbb{R}} \boldsymbol\Pi^1_1$ or with $\sigma$-projective payoff.