Yup, a '1' on a retain will stop even the most eager of titans. The game provides a nice balance of choices to both sides, not least of which is whether to march forward in an attempt to provid a shield for the retiring Miners, or to double slightly less far while trying to suppress the Rangers by lobbing a few shots at them.
Nick and I did discuss finding some way to limit the Eldar air power (as Markonz also suggests), but I am less sure. There are several subtle constraints built in, most of which work in favour of the IG.
Part of the problem with this game is that we created the two armies in a hurry from tournament lists. While the Eldar list is geared for assault, the IG army is much less suited for the scenario. It would probably go much better swapping the SHT company for a Regimental HQ, not just for the additional speed, resilience and formation footprint, but also for the SC reroll which might just have spurred the Leman Russ to assit more
Anyhow, I hope for better success the next time I try it.