Marketplace
A great and fun tower defence game and is apparently free for the weekend however unsure when it actually ends.
iTunes Link: https://itunes.apple.com/au/app/kingdom-rush-frontiers/id598581396?mt=8&ign-mpt=uo%3D4 EXPIRED
Google Play Link: https://play.google.com/store/apps/details?id=com.ironhidega…
You can find daily updates of the free iOS apps at places like iOSnoops and AppAdvice (only a small list here of their pick of "the best").
Another website with a more comprehensive daily listing of both macOS and iOS App Store prices changes, including freebies, is AppShopper, although some of their data entry / filtering is a bit wonky (choosing the "free" apps sometimes includes some that aren't actually free).
Note: Being American-based, some of the apps on their lists may not have the same price or may not even be available at all on the New Zealand App Store, so you need to double-check in the App Store itself.