For your convenience. If this question is asked in chat, member help, etc., simply link this guide!
Ways to Get Apples
(without spending real money)
1. Buy Apples from Other Players
Under Realm > Barter > Search, scroll down to Apples, click Lowest to Highest, and search. This is the most readily available and guaranteed way to get apples. Prices may fluctuate, but usually range from 900-1100 mush. You can probably get apples for less if you advertise in forums/sales chat that you are looking to buy apples. Buying in bulk is usually cheaper than buying apples individually. Personally, I save mush and wait for an opportunity where I can buy apples in bulk for 700-800 mush each.
Occassionally, players may auction apples in forum auctions. Bidding on apple auctions is another way to get apples.
For a guide on how to get mush, check out: https://wolfplaygame.com/forums.php?f=29&t=4603
2. Referrals
Go to Pack > Free Mushrooms and Apples. Send the referral link to friends/strangers, asking them to join WolfPlay. If you are a top referrer of the month, you can win apples.
3. Sell Wolves
To sell a wolf, go to the wolf's page, scroll down, click Manage Wolf, then click Sell. Not many wolves are worth apples, but look for comparable wolves under Realm > Trading Post to get an idea of pricing. The younger a wolf is, the more it is worth.
Chimera and vitiligo wolves are always worth apples.
Other wolves that might be worth at least one apple include:
young female wolves with more than 45 marking rarity
wolves with both a defect and a boost
wolves trained to death grip (at least 925 battle experience)
wolves with over 2500 CP
wolves with over 50 talents
G1 Surpassing Valor, Divine Health or pelt defect wolves
wolves rated 50 in howling and / or wrestling
wolves with a combination of the above traits
4. Breed Wolves
On a wolf's page, scroll down, click Manage Wolf, then click Breed and set a price. Technically, you can get apples this way. However, it's not likely players will actually pay apples for most breedings. Only top custom studs' with hundreds of talents have breedings considered to be worth apples.
5. Sell Items
Items that may be worth apples are:
Items found under Barter > Apples (a free green fern is given to each player on WP's anniversary)
Premium gear
Event decor
Very occasionally, holiday decor that are out of season may sell for an apple.
Valuable explore items (jasmine, toucan feathers, knowledge, etc.) in bulk.
Keep in mind, for items that are always in stock, players will only buy if the price is less than the standard barter price.
6. Auction Currency
You can auction bone fragments or event currency in forums for apples. A bone fragment is typically worth 1 to 4 mush, so you will need to auction at least 250 bone fragments at a time to have a shot at getting one apple.
Event currency is found in explore during March, July (dog bones), August (bloody fangs), October (brains), December (snowflakes).
The value of event currency is highly variable, but ...
7. Full Moon Celebration
On the 5th-9th of each month, there is a Full Moon Celebration found under Realm > Games. For each contest, 1st place (of each allegiance) wins 10 apples, 2nd place wins 5 apples, and 3rd-10th place wins 1 apple.
Howling: You will need a wolf with an Excellent howl rating - either buy or breed one. Not all excellent howlers are equally excellent; in fact, most Excellent howlers cannot make the top ten. It's best to have multiple howlers and test out their howling. On average, a wolf should be able to score at least 25 per howl in order to get in the top 10. Make sure to howl 3 times every day (for a total of 15 times).
Wrestling: Only pups can participate. Use an excellent wrestler pup to get on the leaderboard. You must wrestle 3 times everyday in order to have a shot at the leaderboard, so if there is a spring 1 rollover in the middle of FMC and your wrestler ages, you will need a new pup born on spring 1.
Hunting Tournament: Explore a lot - Chinese pottery is necessary. Your score is determined by the mush earned from battling animals, and both predator and prey count towards hunting score. Your explorer wolves need as much battle, agility, resolve, and battle experience as possible. The higher level the terrain and the more predators, the better.
Spirit Ancestors: Explore a lot and encounter spirit ancestors. Bowing is the best option to please a spirit, but at least one of your explore wolves should have maxed spirituality (more spirituality is better, of course). Low or very low playfulness in explorers also helps.
7. Sell Art
There are a variety of ways to sell art in forums. Opening commissions in your bio and / or blog is another option, though less popular. Have examples ready - a forum art gallery is a good option. Players may not be willing to pay apples for all artists' works, but if you need help on pricing, look at other art shops and / or create a forum poll.
8. Enter Contests / Giveaways
Under Gathering > Forums > Contests, players may offer apples as prizes for giveaways or contests (custom designs, art, writing, etc.). All it takes is luck and talent!
9. Battle Experience Training
WIP
If you have any questions, suggestions, etc., feel free to comment.
Summer 
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Earthquake Moon: 
