You can really earn passive money by playing games online. (Spoiler: they're not VERY fun, but you basically don't have to do anything)
How to Earn Passive Money:
1. Sign up
2. Set it and Forget it! (time = about 20 seconds each)
These sites (mostly Russian) will start you off with free sign-up credits (silver/coins/etc), and you are meant to buy their cheapest money earner (chickens/miners/characters), and let them earn new things passively. Check back later (I picked 45 days since many of them will earn enough to buy a 2nd earning thing) to sell all the things they earned. This money will be divided into credits for more purchases and real cash you can withdraw. Mark your calendars!
Payment methods (Payeer is used by all of them): Bitcoin, Payeer, Qiwi, Yandex, Webmoney, OkPay, AdvCash, Beal, Megafon, MST, Tele2, Visa, Mastercard, Maestro
UPDATE: Payment proof of Golden-Tea!:
I cashed out 0.008 BTC or about $110 USD!! Remember to buy more bushes every month!
https://blockchain.info/address/16Jv4T5JxTT7Qi6SQDumzJuRXmt2XfckHy
| Name | Buy these: | which will earn these: | Profits after 45 days*: |
| Golden-Tea | bushes | leaves | about $5.50 USD |
| Elvengold | buildings | earnings | 900 gold |
| Ressources | weapons | meat | 180 |
| Ruby-Mine | |||
| Fish-Farm | fishing poles | fish | 76500 |
| Golden-Farm** | 75 | ||
| Goldenbirds2 | birds | eggs | 0 |
| Fruitmoney | trees | fruit | 3.07 |
| Online-Ogorod | |||
| Motormoney | cars | money | 3.9 |
| Dragoneggs | dragons | eggs | |
| Rich-Fishing | fish | ||
| Tropic-Birds | birds | eggs | |
| Azska-Eco** | gas station | fuel | 44 silver |
| Money-Birds | birds | eggs | 1065 silver |
| Azgard | characters | earnings | 93 |
| Money-Gnomes | gnomes | ore | 845 silver |
| Teremmoney | characters | earnings | 18 rub |
| City-Farm | buildings | earnings | 2253 |
| Money-Aligarch | workers | ore | |
| Fruit-Town | bush | fruit | |
| Egyptgames | workers | earnings | |
| Money-Birds | birds | eggs | 15.84 silver |
| Univer-Monstr | monsters | frights | 270 silver |
| Diamond-Hunter | mines | diamonds | 300000 gold |
| Paper-Island | characters | earnings | 1037 |
| Cowfarm | 12 rub | ||
| Rich-Town | buildings | taxes | 9295 |
| Pokemon-Money | pokemon | pokemonet | 30 silver |
| Goldenbirds | 0.01 silver | ||
| Weblider | 0.3 rub | ||
| Kapitalof | 0.3 rub | ||
| Profit-City | buildings | earnings | 2315.81 coins |
| Market-Hit** | buildings | earnings | 6.9 rub |
| Bestferma | buildings | earnings | 17.31 silver |
| Push-Game | characters | earnings | 4.5 |
| Cat-And-Mouse | cats | mice | 195 |
| Sea-Treasures | characters | pearls | 27 |
| Monopoliya | cafe | earnings | 30.273 coins |
| Heroes-Birds | birds | eggs | 919.95 |
| Fishing-Biznes | 51.54 silver | ||
| Chickens-Farm** | chickens | eggs | 86.39 |
| Smurfiki-Best** | ? | ||
| Profit-Birds** | birds | eggs | 21 |
| Golden-Mines** | miners | ore | 20 gold |
| Goldenmines** | miners | ore | 42 gold |
*Unfortunately this kind of data is hard to gather. Every site has it's own in-game currency and rarely tell you the conversion rate to Russian rubles. Numbers without units likely means "silver." Blank spots means I tried my best.
**No free sign-up credits. You need to collect the daily bonus credits to buy your first "thing." Good Luck!