Video game industry tracker NPD Group put out its sales trend report for the month of May yesterday. If you have any skin in this game as an investor, it pays to heed the lessons that last month's tutorial had to offer.

1. Take-Two is still No. 1
Grand Theft Auto IV, Take-Two Interactive's (NASDAQ:TTWO) action-packed blockbuster, led the pack by moving 1.3 million copies domestically last month. This doesn't come as a surprise, especially after the game set a one-week sales record during its April debut.

2. Don't mess with Mario
Nintendo (OTCBB: NTDOY.PK) cynics figured that Take-Two's gain would be Nintendo's loss. The salty Grand Theft Auto is only available for Microsoft's (NASDAQ:MSFT) Xbox 360 and Sony's (NYSE:SNE) PlayStation3, so would shoppers still favor the Wii over the other next-generation consoles? They did. Selling 675,100 units in May, Nintendo outsold the PS3 and 360 combined. The groundbreaking debut of Wii Fit and the allure of Mario Kart with a wheel attachment for the motion-sensitive Wii controller helped Nintendo, which on the software side accounts for four of the six best-selling titles -- and six of the top 10 -- for May.

3. It's not in the game, EA
Silence is never golden in the competitive software industry, so what can Electronic Arts (NASDAQ:ERTS) say when its name wasn't behind any of the 10 top-selling titles in May? The best way to get its name back into the chart would be to actually offer a realistic buyout value for Take-Two. The longer it waits, the stronger Take-Two gets on its own.

4. Needs more iron
Marvel (NYSE:MVL) is another big winner. Sega's Iron Man for the PS2 wound up being the best-selling non-Nintendo game after Grand Theft Auto IV. This normally wouldn't be major news, but since last month's film was the first self-produced feature by Marvel itself, there is a lot more money at stake as the franchise grows through various revenue-generating channels.

All in all, it was a healthy showing for the industry. Video game sales soared 41% over last year's May showing. You can thank Take-Two and Nintendo for the boost, but it's comforting to know that an iffy economy isn't easing our grip on the controller's trigger.

Other ways to get into the game:

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.