The original idea I had was a sort of spin on those games where the objective is to increase numbers exponentially. The player would be able to construct buildings and recruit people to automate processes while they aren't using the app. Hence the portrait mode. I couldn't decide in the first month or so if this would be a game where the player is even present.
In August it went landscape mode and I had added a few different job roles like workers (who repair the wall) and lumberjacks (strangely named scavengers at the time). Around this time I realised I could turn this base-defence game into a retro simulation of a post-apocalyptic scenario.
I started releasing test builds to some of my friends and family (to their annoyance). The game was so incomplete that they didn't understand what to do without an explanation of it. Beta testing at this stage ended up being useful for fixing the occasional bug but not much more than that.
By September I was frantically adding features to the game, such as a side on view of the combat between the zombies and guards, because I knew I was starting university by the end of the month. Focusing my time on the first year, I would leave the game almost untouched until June 2019.