8. Base Wars
It seems as though the sports simulation limited the scope of the sports genre considerably. Back in my day for every Madden and Joe Montana game there was Mutant League Football, Arch Rivals and of course Base Wars. Base Wars combined the game of baseball with a pretty well developed robot building system allowing players to have a lot of fun building various Real Steel style sluggers and hurlers. Upgrading equipment and combining parts allowed the player to make some pretty unique robots to take the field with. The guts of the game have a lot to offer even a modern day player that enjoys Sims style character maintenance with a definite sports feel.
Update: Base Wars would capitalize on next generation online multiplayer formats. Not only can players spend hours building the perfect robotic player baseball game, focusing not only on play ability but combat skills and weapons as well (after all, with War in the title, combat should be a given), the combat element made stealing a base an adventure. If the MLB could find a way to get involved on some level, there could be an interesting IP that actually helped baseball in the long run.