I always found such a shame that Encircle of Stalingrad (v2) by andreigiurea was so easy to beat: just capture the undefended supply hexes south and the whole encirclement comes to a grinding stop. So I added a few units and specialists to the Soviets, tweaked the AI to defend the supply positions while still giving priority to the attack. I also weakened the Romanian line a bit (historically it never was at full strength at that time) and gave you a few more German specialists to give you some freedom to decide for yourself where you are going to reinforce. The result is that the Soviets are capable of encirclement this time... So this scenario is a lot more fun IMHO.