The zombie survival game? That was one of the first ones I did. I think some of it is a bit out of date and/or suboptimal, as it was done before the Tilemaps feature got added; I also found several places where the instructions were unclear and there were mistakes in the sample code. Honestly, those things weren't so bad they killed the experience, because they did force me to dig around and correct the issues myself. So while it's not bad, Tilemaps (and the poorly-documented ScriptableObject approach to overriding the Tile/TileBase classes to get your own tile behavior) are really valuable additional research items.