Of course it's okay to lie in a *game* of diplomacy. We all transform into a false reality in which everyone is given permission to lie to each other, so once you know everyone can and likely will lie at some point, you basically transcend the fact that it is lying, it's merely playing the game itself. This is similar to the fact that life is difficult, but once you fully accept that, you transcend the fact that life is difficult, life is merely life, since difficult is part of the definition, and thus there is no need to focus on life being difficult anymore. So, we're not lying, we're merely playing a game of diplomacy, no more, no less.