Force swapping of certain stopped processes

Maybe try a command like this to temporarily use a lot of memory to force Chrome (and everything else) to swap out before starting minecraft

dd if=/dev/zero conv=block cbs=1024m of=/dev/null bs=32m count=32

I wouldn't bother; other processes will be paged out automatically when there's memory pressure. The kernel uses a "least-recently-used" scheme for deciding what should be paged out next, and if you stop Chrome with SIGSTOP, it won't be able to use any of its pages, so after awhile they'll be kicked out of RAM if Minecraft needs more.