Based upon your experience playing wargames. The reality is that Japan had to secure sources of oil and rubber or its economy was going to collapse. Attacking Siberia would gain nothing for Japan. Before you say ‘but the Axis would have won the war’ your basic assumptions are based on fiction. That Milton Bradley, GDW, Avalon Hill, SPI or whatever game designer allows for an action to be possible within the confines of a game has nothing to do with what actually was possible. That a game allows for such actions reveals flaws in the game, not possibilities in reality. For example, take a look at your idea that Japan would be able to do among other things “push into India”. It may seem very plausible when pushing counters around on a map, but a look at what happened in reality when Japan tried doing this in Operation U-Go is illustrative. They starved to death.