I understand that this would be a giant pain in the butt, but it'd be really neat if certain blocks had special powers. For instance, if a tnt hides next to a redstone block, it spawns a tnt that can blow up the seeker. Another idea might be that anvil blocks run slower, but maybe they get knockback IV when they hide, or iron, gold, and diamond blocks get to wear a chestplate of their respective block, making them a bit heartier. The powers are entirely up to you, but I personally think it'd be really neat for the hide and seek to be a bit more strategic than "stand still for 5 minutes and hope the seeker doesn't find you". Failing this, can we just have more blocks to hide as? Maybe leaves, sponge, glass, quartz etc?