If you're a professional StarCraft 2 player, Tuesday, March 12 has been a looming, potentially terrifying, date on the calendar.

Today, Blizzard Entertainment released Heart of the Swarm, its first-ever expansion pack overhaul for its globally popular sci-fi military strategy game, StarCraft 2. It is also the day when professional StarCraft 2 players will find out whether they'll be able to continue living their dream. When a new game is released in a series like StarCraft, the old game becomes obsolete, as every tournament switches to the new game. Dominant players from the old days may not be competitive anymore, and moderate players might find that the new game is much more favorable to their play style.

"Players live on borrowed time and they know it," said pro player and commentator Geoff Robinson, captain of the StarCraft division of Evil Geniuses, in an e-mail.

"Being nervous about losing your job or fading away is something that constantly plagues them," Robinson said, a fear that can become all too real when a familiar game is swapped out for a new one.

Jung Jong Hyun, who goes by the handle "Mvp," was a moderately talented professional in the first StarCraft game. But when StarCraft 2 came along, he became an unstoppable four-time champion of the most competitive league in the world, the Global StarCraft League in South Korea. Jung has now won more than $300,000 playing StarCraft 2 since 2010, and not even the most dominant StarCraft players have been able to transition to StarCraft 2 nearly as successfully.

Such big winnings are not typical. Most professional players receive a comparatively small salary similar to what you'd expect from an entry-level office job. They live, practice, and study inside their "team house." It's not a bad living, but there's not much of a fall-back plan for players who can't compete anymore.

The competition is fierce, and secretive. Prior to the launch of Heart of the Swarm, hundreds of top players have been furtively practicing in the beta with usernames like "|I|I|I|I||I|||III." Called "barcode names," they're meant to obscure the identities of the players so they can experiment with the game's rule changes, and hone their strategies, in secret.

Although it is an add-on content package for StarCraft II and not an entirely new game, Heart of the Swarm will introduce many new army units for each of the game's three races and make radical changes to many other elements. The dominant strategies and play styles currently used by top players are guaranteed to change, and that poses a problem for players who have been successful under the old paradigm. If the game no longer plays to their individual strengths, then they might be replaced by someone who has adapted to the new styles.

For e-sports players, it can be something analogous to what Tiger Woods would have to deal with if the PGA suddenly decided that all the fairways on their golf courses were too long. Golfers who had gained an advantage in the past by having a long drive would lose that edge, and players with great putting and chipping skills would gain the upper hand.

If Heart of the Swarm is scary for some players, it represents opportunity for others.That would likely never happen in golf, but for pro gamers it happens all the time. The courses they play on do change, and they'll have to learn to use new types of clubs. Not everyone will be able to adapt.

"We make our money solely off of how successful we are and how much attention we get," said Evil Geniuses captain Robinson. "If something challenges either, or both in this case, because of change or the need for adaptation then we are very afraid."

But it's an ill wind that blows no good. If Heart of the Swarm is scary for some players, it represents opportunity for others. Players and teams that have long survived at the fringes of StarCraft competition are viewing Heart of the Swarm as a time of renewal, a moment when they can finally make their move to the top.

"It’s definitely true that Heart of the Swarm will bring a new paradigm to the StarCraft 2 e-sports scene, and that some players who enjoyed major success [before] may not experience the same success in the expansion," said Amelia "Sunset" Savery, a spokesperson for StarCraft 2 team ROOT Gaming.

"Many players may find it difficult to adapt or break habit in the face of new units, maps, and strategies," she said.

Composed mainly of North American players, ROOT Gaming has never been able to compete consistently against the top South Korean players that dominate the sport. But Heart of the Swarm could be an opportunity for smaller teams to make a move up the totem pole.

"We believe our players are not only good mechanically, but that they possess skills which can not be taught – creativity and adaptability," said Savery. "These are the skills that are crucial to early success."

At the end of its three-year lifespan, vanilla StarCraft 2 has been mastered. The dominant strategies have been set in stone, and every problem or challenge has an established solution. Creativity is not something there is much room for. As Heart of the Swarm launches, such adaptability may prove to be a more important asset than mouse-speed or strategic decision-making. Players who can innovate and surprise their opponents will have the best odds in a tournament setting where psychology and subterfuge are just as important as mechanical skill. For spectators who enjoy watching StarCraft matches, the uncertainty should prove thrilling.

"We expect even bigger, more exciting things this time around," said Savery. "Not only are we not afraid of these sorts of changes, we embrace them."