The letters are spawnd in a cycle of 1) target letter 2) wildcard 3) wildcard. But the last bug fix with the spawner I added introduced a bug which meant a letter couldnt spawn if the max number of zombies existed in the play area. I (think) I fixed that now, so all of the words can be found with an update that essentially purges zombies to ensure that a required letter acn be spawned. I'm posting that bug fix update today. But there is another problem with the gameplay itself - and that is actually finding the letter in the play area - it can take some time. so an added feature (that I cant do during the Jam review) would be to include a 'compass' that would hint at the area to go to find the zombie/letter. There are a whole list of other things to fix too! :) I also havent had the time to play test on different browsers, sorry! That is also something to add to the list. :P