Function encode_simulation_vctower 

pub fn encode_simulation_vctower(
    sim: &Simulation,
    app_version: &str,
    saved_at_ms: f64,
) -> Result<Vec<u8>, String>

Writes a game as .vctower file bytes: Simulation::serialize, stamp_save and encode_vctower in one call, without holding the whole save in memory at once. The engine has no clock or version of its own, so pass your host’s name and version and the time in milliseconds since the Unix epoch.