Play free-to-play, with microtransactions games
Free-to-play games (commonly known as F2P) can be freely downloaded, installed and played without paying. Some free-to-play games offer the player the chance to buy items or services for real money (MMORPGs are the perfect example) in an online in-game marketplace. The cost of such items is often very low, hence the "micro" in "microtransactions". These items or services range from increased experience gain items to cosmetic enhancements, additional content, more character slots, etc.
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The Settlers Online
strategy / MMORTS
Blue Byte Software

Dead Maze
RPG / MMORPG
Atelier 801

Spellweaver
card game / collectible card game
Dream Reactor

Hattrick
simulation / management
Hattrick Limited

KROSMAGA
card game / collectible card game
Ankama Studio

Eutopia
RPG / MMORPG
Max Breedon

Second Life
simulation
Linden Lab

Soda Dungeon 2
RPG / turn-based tactics
AN Productions

Brawlhalla
action / fighting games
Blue Mammoth Games

Heroes Of Newerth
strategy / MOBA
S2 Games

HEX: Shards of Fate
card game / collectible card game
Hex Entertainment

Imperia Online
strategy / MMORTS
Imperia Online Ltd.

PlanetSide 2
action / MMOFPS
Daybreak Games

Soviet Jump Game
platformer / brawler
Fantastic Passion

Stronghold Kingdoms
strategy / MMORTS
Firefly Studios

Travian: Legends
strategy / MMORTS
Travian Games

Warspear Online
RPG / MMORPG
AIGRIND

Magic Duels
card game / collectible card game
Stainless Games

Trove
RPG / MMORPG
Trion Worlds

Supremacy 1914
strategy / wargame
Bytro Labs

Anno Online
strategy / MMORTS
Ubisoft Blue Byte