Alright so here's the deal with unlocking those alternate storylines - you actually can't get them all in one go (this is by design to encourage replaying different perspectives). The whole system revolves around completing specific objectives for each faction which makes sense since each ruler had their own crucial moments that could've changed history.

For the shu path, you'll need to stand your ground against cao cao at changban instead of retreating (this really fits liu bei's character development). Wei's route is probably the most involved since you need three key moments - saving dian wei during that chaos at wan castle, getting to guo jia quickly enough at mt. Bailang, and intercepting huang gai before he can launch that famous fire attack at chibi (timing is crucial here). For wu, it's all about protecting the sun family legacy by saving sun jian at xiangyang and rescuing sun ce during that rebellion.

You'll need to finish the game once first to unlock new game+, which lets you replay from chapter 3 onward (this saves you from replaying early tutorial sections). Each faction needs its own separate playthrough, but here's something interesting - the choices you make actually connect to historical what-ifs that could've dramatically changed the three kingdoms era. When you're trying to save characters, remember that most rescue missions have a hidden time limit even if it's not shown on screen (keeping an eye on ally health bars is usually a good indicator).

Remember that once you trigger a hypothetical route, you're locked into it for that playthrough, so maybe save beforehand if you want to see both outcomes. The alternate scenarios really show how different the whole three kingdoms period could've been if just a few key moments had played out differently.