More examples of the Play to Donate model.

Tree Planet 3

This is the first in the Korean mobile game series that is available in English. Tree Planet 3 is a tower defense game where you defend a baby tree from waves of monsters and possessed livestock. You do this by recruiting stationary  minions to beat down the monsters as they parade along the side of the path or paths to the tree. You also have a tree hero that has some movement and special abilities to slow or damage monsters.

Stages are a mobile friendly 3-5 minutes long, and finishing a set of three stages results in a real tree being planted (with proof of planting provided).

Part of the revenue for the game and the planting comes from the game's freemium pay-to-win model: beating a stage provides rewards to slowly unlock and upgrade new heroes, but rewards can be purchased for $USD right away. The rest comes from sponsorship from NGOs and from corporations that benefit from trees being planted, such as a paper company in Thailand that will buy back the trees later, and a solar power company in China that uses trees to catch dust that would otherwise blow onto their panels.

I greatly enjoy Tree Planet 3. For some stages I've managed to set up minions to win almost without looking, but for others I'm still working out a viable strategy. The monsters and maps are varied in function as well as look, which is better than I expect from most mobile games, let alone a charity one.

Aside from purchasing upgrades, play doesn't seem to have any effect on the revenue generated for the planting system, even though playing supposedly causes planting.  Is the sponsorship paid on a per tree basis? I have questions, but the faq is in Korean only.

Aside from the sponsorship there were no advertisements such as a rolling banner; I would love to know how that affects a game like this.

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Play to Cure: Genes in Space

This game was commissioned as part of a 48 hour programming event by body called UK Cancer Research, if I'm recalling the details correctly.

In a stage of Genes in Space, the player plots a course through a map based on some genetic data that needs analysis.  Then the player pilots their spacecraft in an over-the-view through the map with the genetic data showing, as well as the path they charted.

The goal of the player is to fly through as much of the genetic data as possible. The goal of the designer is to use multiple players charting and flying through the same map to find where the abrupt changes in genetic information occur, which will match with the points where an optimal player changes her flight path.

Aside from previously mentioned charity games, this one has the appeal that gameplay is actually creating value, rather than using your efforts to moving money from somewhere to somewhere nicer. By playing through a level, you are in fact contributing to science, and the rewards to upgrade your ship and climb a leaderboard are related to the density of the genetic data is that you manage to fly through (which in turn relates to quality of the contribution to analysis)

I enjoy the flavour of the game, and being able to paint my vessel to look like a bumblebee gummyship gathering genetic pollen.

However, the game was rushed and even after patches this is painfully obvious. It is unclear how ship upgrades help you, aside from the occasional meteor storm event that occurs after gathering, and which seems unnecessary and tedious.

The flight portion of the levels is extremely short: about 30 seconds to play, which follows 60 seconds to chart and 60-90 of loading screens and menus. By prolonging the flights by a factor of 2, I would be spend more time on the best part of the game and probably make better flight decisions, at the cost of processing maps 15-20% slower. Remove the meteor storm event and make ship upgrades aesthetic only, and even that loss is gone.

By far the worst problem is a bug where sometimes a blank map is presented, on which no route can be planned, and flight never ends. This could be because all the generic data has been analyzed, but I suspect it's an issue with corrupt genome data.

What elevates this from an annoyance to a deal breaker is the inability to do anything about it. There is no option to scrap the map and try a new one, and sometimes even uninstalling, then resetting the phone, then reinstalling fails to fix the issue.

If I'm right about the source, the problem could be cleared up by giving players more autonomy regarding their contributions. An option to manually  download a new map, or several maps at once for offline play should be simple. It would also fix some of the loading issues and improve gameplay, especially if players could go through multiple genomes in one long flight.

One final note: I know finding these breakpoints in a genome is ineffective for a machine because I looked it up, but this player data should make for a fantastic training set.