Even though it is undergoing a transition from consoles to digital platforms, the gaming industry has racked up substantial gains this year. Stocks of major gaming companies have shown double- to triple-digit gains this year. Moreover, the exchange-traded fund (ETF) industry's first fund dedicated to gaming – the ETF Managers Trust Video Game Tech ETF (GAMR) – is up by approximately 42% this year.

Research firm Goldman Sachs, which recently began coverage of the sector, stated that video game publishers are "in the middle of a renaissance." According to a report released by consulting firm PricewaterhouseCooper (PwC), global revenue from video games is expected to hit $93.2 billion by 2019. The firm estimates that global distribution for digital games will reach $12.9 billion during the same time period. That figure represents 19.6% of overall revenue. (See also: Power Up Your Portfolio With Video Game Stocks.)

Here are three gaming stocks that have been the biggest gainers so far this year.

Activision Blizzard, Inc. (ATVI)

Shares in the maker of popular games such as "Call of Duty" and "World of Warcraft" are up by 76.6% this year. After acquiring app games company Kings Digital last year, Activision Blizzard has forayed into other emerging businesses such as eSports. This should bode well for its bottom line. According to Christopher Merwin from Goldman Sachs, earnings from eSports could "far surpass" spending on established businesses such as Major League Gaming. During its latest quarter, Activision Blizzard reported $1 billion from in-app purchases. The company has said that it is revamping content in its existing games to promote spending. (See also: Activision to Surge on New Game: Piper Jaffray.)

Take-Two Interactive Software, Inc. (TTWO)

Take-Two Interactive stock is already up by 102.4% this year. According to Goldman Sachs, Take-Two is in a "sweet spot" for game releases. Goldman's analyst also noted Take-Two's investment in new content such as "Grand Theft Auto" and its efforts to monetize existing content such as "Red Dead." The company is also bringing existing titles to new devices, such as Nintendo Co., Ltd's (NTDOF) Nintendo Switch. Take-Two's president Karl Slatoff said that the company was "intrigued" and "optimistic" about the platform. According to reports, Nintendo has sold 5 million Switches so far. Take-Two also has a healthy cash position of $1.3 billion. (See also: Take-Two's Forecast 'Better Than Feared,' Shares Hit Record.)

Electronic Arts Inc. (EA)

By most yardsticks, Electronic Arts is a pioneer in gaming. However, the company lags other players in the shift toward mobile and digital. Its digital sales rose 23% during the first quarter of 2018 as compared with the same period last year. Of Electronic Arts' overall revenue, 61% came from digital sales. This should help with gross margins because digital games have lower fixed costs and sustained future profits. It is no wonder then that investors have bid up Electronic Arts shares by 50% since the start of this year. (See also: Video Game Stocks Level Up to All-Time Highs.)

Want to learn how to invest?

Get a free 10 week email series that will teach you how to start investing.

Delivered twice a week, straight to your inbox.