Pretty sure doing things fine
Also the reason they have been redoing many of the old scenarios in the book because of how easy they were.
I'll join in and say that you're probably doing something wrong. That game clearly isn't 'too easy'.
Are you sure you're following all the rules?
0. Spawn in buildings
1. Ranged weapon hit priorities.
2. Sewer spawns (particularly with respect to how the 'survivor on a tile' aspect works (as well as just spotting them in the first place)).
3. One search per survivor per turn (even if it's free).
4. Spawning at all spawn sites every turn.
5. Ensuring you place noise tokens when noise is generated.
6. Remembering that each survivor = 1 noise token.
7. Each Plenty Of Ammo cards only allows you to re-roll once per attack (but multiple PoA cards can be 'stacked'), and you may only re-roll all the dice for that attack, not some of them.
8. Zombie reactivations (both from spawn cards and from running out of minis)
9. Zombie groups splitting.
10. Runners get two actions per turn.
11. Zombies move towards survivors they can see in favour of noise.
12. Choosing only one skill at Orange and Red.
13. Reloading weapons that need reloading (Sawed Offs and Ma's Shotgun).
14. Only searching inside buildings.
15. Leaving a zone that contains zombies costs 1 extra action per zombie.
16. Dice rolls are considered individually not added up.
If you manage to finish the first scenario (City Blocks), respecting the rules, with no wounds (as defined by 'too easy') then please make a youtube video of it as there are a lot of people who could use your tactics.
That game is brutal.