[How does an old player return to playing]

So this is my most played game on steam. I played it way back when the level cap was 20 up to when chaos was introduced. However I eventually got tired of what was being done with the game and stopped playing. I want to jump back in and give it another go but I can't get past the barrier of not knowing where to start. Apparently I got to chaos 6 before quitting and have some gear from that but I have no idea what the metal is now and I don't remember what heroes I used and which towers. I have 2 bags full of shards that ivy held onto. Any tips for what to do to get back into it without being overwhelmed?

[Assassins need looked at]

There are many problems with the assassins but there are 2 major ones in my opinion.

1) They get rid of half of the game.  The thing that made these games great was that they were action rpg/tower defense games.  When you throw an unreasonable amount of assassins at heroes, it turns into just standing in front of your towers and hoping your defenses hold up.  You can't attack and you can't repair during waves because you are constantly disabled by the assassins.  I've had times where every other enemy is dead including bosses, but I still have 5 assassins left.  It forces people to play like they are using an afk build.  This is not fun.

2)  It limits the number of hero builds you can use at higher difficulties.  You NEED hero health as a stat on pretty much all of your armor pieces or you die very quickly from the assassins.  This means you only have one stat you can use to benefit your active hero playstyle.  You can no longer use cool hybrid builds like hero damage/crit because you have to only pick one of those to use since the other spot is taken by health.  Not that it matter since you are barely attacking in chaos v anyways.