Director Gavin Hood's sci-fi epic Ender's Game opened to a solid $28 million in North America, but it will need strong legs in order to make back its pricey $110 million budget -- a potentially difficult task considering that Thor: The Dark World enters the domestic marketplace next weekend. 
 
 Ender's Game, receiving a B+ CinemaScore, is based on the best-selling novel of the same name by Orson Scott Card, whose anti-gay comments have riled a lot of people. Many consider Ender's Game to be a YA property, although Card said he wrote it for adults. He seems to have a point: 58 percent of those going to see the movie were over the age of 25. 
 
 VIDEO: Harrison Ford on Bringing 'Ender's Game' to the Big Screen 
 
 A co-production between Summit Entertainment, OddLot Entertainment and Digital Domain, Ender's Game hopes to launch a franchise. It stars Asa Butterfield, Harrison Ford, Ben Kingsley, Viola Davis, Hailee Steinfeld and Abigail Breslin. Set in the near future, the story revolves around a young boy (Butterfield) who is recruited by the military to stop an alien race from destroying the world. 
 
 Ender's Game is a sizeable gamble for Gigi Pritzker's OddLot, which financed much of the movie and dispatched sister company Sierra/Affinity to sell it internationally. The film is off to a nice start overseas, grossing $9.1 million so far from 15 markets. (The book was never as popular internationally.) 
 
 The movie opened in a raft of markets this weekend but saw subdued results because of Thor 2, which launched to a massive $109.4 million as it opened in 70 percent of the foreign marketplace this weekend. Thor 2 opens next weekend in North America. 
 
 Outside of The Hunger Games and Twilight film franchises, YA film properties have struggled, with The Host, Beautiful Creatures and Mortal Instruments: City of Bones all flopping this year. 
 
 Elsewhere at the box office, Paramount's Jackass Presents: Bad Grandpa has quickly turned into a box office hit, falling less than 38 percent in its second weekend. The R-rated comedy grossed $20.5 million to end the weekend with $62.1 million in domestic grosses. It came in No. 2 and had no trouble beating sexagenarian comedy Last Vegas and Free Birds. 
 
 Bad Grandpa, costing a mere $15 million to make, is also impressing internationally, where it earned $6 million from 19 markets this weekend for an early foreign total of $17.6 million and a worldwide total of $79.7 million. 
 
 From CBS Films and Good Universe, Last Vegas, starring Robert De Niro, Michael Douglas, Morgan Freeman and Kevin Kline as four friends in their 60s who travel to Las Vegas for a bachelor party, came in No. 3 Friday with a better-than-expected $16.5 million. The $28 million film should have an especially strong multiple since it is being fueled by older adults, who don't rush out to see a film opening weekend. 
 
 CBS Films believes Last Vegas will serve as strong counterprogramming throughout the month. In August 2012, Hope Springs, starring Meryl Streep and Tommy Lee Jones, opened to a modest $14.7 million on its way to earning $63.5 million domestically and a hearty $114.3 million globally. 
 
 OVERSEAS BOX OFFICE: 'Thor: The Dark World' Opens to Huge $109.4 Million 
 
 Free Birds, costing $55 million to produce, performed on the low end of expectations, grossing $16.2 million. The family film marks the first animated 3D pic from Relativity Media, who partnered with Reel FX in making the movie. 
 
 The Thanksgiving-themed movie, marking Relativity's first foray into the animation business, is about a pair of turkeys who travel back in time to prevent their kind from becoming the traditional holiday meal. The voice cast is led by Owen Wilson, Woody Harrelson and Amy Poehler. 
 
 Both Free Birds and Last Vegas earned A- CinemaScores. 
 
 Steve McQueen's 12 Years a Slave continued to build momentum, moving up the chart to No. 7 as it expanded into a total of 410 theaters in its third weekend, grossing $4.6 million for a North American total of $8.8 million for Fox Searchlight. 
 
 Twitter: @PamelaDayM ||||| Hailee Steinfeld, left, and Asa Butterfield star in "Ender's Game," which was No. 1 at the box office this weekend. (Summit Entertainment) 
 
 This weekend Hollywood was again unable to lure teens to the multiplex in droves, as "Ender's Game" became the latest young adult adaptation to open with modest ticket sales. 
 
 The pricey sci-fi flick debuted with a so-so $28 million, according to an estimate from Lionsgate's Summit Entertainment, which distributed the movie. While the opening is far from disastrous -- it's actually $5 million more than industry predictions suggested -- it still isn't great given that the studio was likely hoping "Ender's Game" would launch a successful Y.A. franchise. 
 
 Meanwhile, in somewhat of a surprise, Johnny Knoxville's hidden-camera prank flick "Bad Grandpa" was the weekend's runner-up. After debuting at No. 1, the film saw its ticket sales tumble only 36% this weekend to $20.5 million, raising the picture's 10-day tally to $62.1 million. 
 
 PHOTOS: 'Ender's Game' premiere in Los Angeles 
 
 Heading into the weekend, pre-release audience surveys indicated the 3-D animated movie "Free Birds" would easily top the comedy "Last Vegas." Instead, the latter film starring Morgan Freeman, Robert De Niro, Kevin Kline and Michael Douglas came in just ahead of the family film with $16.5 million -- a healthy start given its modest $28-million budget. "Free Birds," which cost $55 million to make, opened with $16.2 million. 
 
 Based on Orson Scott Card's bestselling 1985 novel, "Ender's Game" stars 16-year-old newcomer Asa Butterfield as a boy attempting to protect mankind from aliens. Though the movie is aimed at teenagers, it attracted an older crowd this weekend as 54% of the audience was over the age of 25. Those who saw the film assigned it an average grade of B+, according to market research firm CinemaScore. Even if the movie generates positive word-of-mouth, it will still have to contend next weekend with the sequel "Thor: The Dark World," which is expected to be a big hit. 
 
 "The real key to the success of the movie is going to be how we hold next weekend," acknowledged Richie Fay, Lionsgate's president of domestic distribution. "But if we can survive against 'Thor,' I think we’ll be in good shape." 
 
 The movie is the latest in a series of films made for the under-18 crowd that have failed to connect at the box office. In the wake of the massively popular "Twilight" and "Harry Potter" franchises, "The Hunger Games" has been one of the only young adult novel adaptations to work at the multiplex. (The next entry in the "Hunger Games" series, "Catching Fire," is set to hit theaters with a possible $150 million opening on Nov. 22.) This summer, the second installment in the "Percy Jackson" series grossed just $67.3 million in the U.S. and Canada -- roughly $20 million less than the first film collected domestically in 2010. Other Y.A. casualties have included "The Mortal Instruments: City of Bones," "The Host" and "Beautiful Creatures," none of which ultimately made it above $32 million. 
 
 PHOTOS: Scene from 'Ender's Game,' and director Gavin Hood on battle scenes 
 
 "Ender's Game" cost a pretty penny to produce -- about $110 million, co-financed by OddLot Entertainment, the visual effects company Digital Domain and Summit. However, the financiers insist that international pre-sales took care of the majority of the film's production costs, meaning they would not have much on the line financially. 
 
 While "Ender's Game" played to an older-than-expected demographic, "Last Vegas" resonated with exactly the crowd distributor CBS Films anticipated: the AARP set. About 83% of moviegoers were over the age of 25, and 47% were over 50. Though critics loathed the movie, filmgoers enjoyed it, giving the film an average A- grade. 
 
 Financed by CBS and Good Universe, "Last Vegas" follows four older gentlemen who travel to Sin City for a bachelor's party. The movie played best in the South -- where Freeman’s movies are often popular -- and the Midwest: On Saturday, the movie sold more tickets at a theater in Oklahoma City than any other venue in the country. 
 
 “We always thought this would be a fly-over movie because movies about Vegas -- which is a destination holiday location -- tend to do better in middle America,” said Steven Friedlander, executive vice president of theatrical distribution for CBS Films. 
 
 As for "Free Birds," the movie is the first partnership between Relativity Media and Reel FX Animation Studios. The movie is the first in a slate of planned low-budget animated films to come from the two companies. 
 
 The movie follows two turkeys (voiced by Woody Harrelson and Owen Wilson) who are attempting to save their kind from ending up as Thanksgiving dinner. Given the film's subject matter, Relativity is hopeful the movie will play well over Turkey Day. Though the movie didn't get off to a fantastic start, it earned an average grade of A- from moviegoers, and no other films for little kids are slated to be released until Nov. 27. 
 
 ALSO: 
 
 'Last Vegas' is not necessarily about the city of old 
 
 'Ender's Game' to top 'Free Birds,' 'Last Vegas' at box office 
 
 ‘Ender’s Game’ director Gavin Hood on sci-fi battle sequences, integrity ||||| It’s taken over two decades for Orson Scott Card’s classic sci-fi novel Ender’s Game to make it to the big screen, but all the built-up anticipation didn’t lead to out-of-this-world box office numbers. The film adaptation debuted with $28 million from 3,407 theaters on its first weekend — a start in the same range as Will Smith’s misfire After Earth, which opened with $27.5 million earlier this year. Summit and OddLot Entertainment spent $110 million on the space adventure starring Asa Butterfield and Harrison Ford, but Ender’s Game will need great legs domestically and strong returns overseas to justify its cost (and any potential sequels). 
 
 Of course, the film didn’t bomb the way other YA-adaptations like The Host, Beautiful Creatures, or The Mortal Instruments: City of Bones have recently, but its opening was nowhere near the debuts of Twilight or Hunger Games, both of which had less expensive first editions than Ender’s Game. Notably, both of those films targeted young women primarily, while Ender’s Game‘s audience was 58 percent male and 54 percent above the age of 25. Crowds issued the film an average “B+” CinemaScore grade. 
 
 Jackass Presents: Bad Grandpa held up very nicely in second place, dropping just 36 percent to $20.5 million. That is by far the smallest second-weekend drop for any of the Jackass films, and it gives Paramount’s $15 million prank comedy $62.1 million total after ten days. If Bad Grandpa continues to maintain great holds at the box office, it could exceed $100 million total. Take that, Oscar season! 
 
 Third place belonged to CBS Films’ Last Vegas, which opened with $16.5 million in 3,065 theaters. The film, which stars Morgan Freeman, Robert DeNiro, and Michael Douglas, opened ahead of last year’s Hope Springs, another film targeting the oft-ignored 45+ demographic, which started with $14.7 million on the way to $63.5 million total. Thanks strong word-of-mouth and an “A-” CinemaScore grade, older audiences may flock to the theater gradually over the next few weeks and push Vegas‘ total as high as $60 million. For a humble $28 million comedy, that’s a lot like hitting the jackpot. 
 
 Free Birds started in fourth place with $16.2 million, and though the film wasn’t a total turkey, its box office left a lot to be desired. Relativity’s $55 million animated entry, which features the voice of Amy Poehler, opened in an ultra-wide 3,736 theaters with virtually no family competition (Cloudy With a Chance of Meatballs 2 arrived six weeks ago), but it could only muster a $4,336 per theater average. On the bright side, Free Birds did spike 82 percent from Friday to Saturday, which suggests that it is playing well with young tots during matinee shows, and it should hold up well as Thanksgiving approaches — especially with an “A-” CinemaScore. It may earn back its budget yet. 
 
 Rounding out the Top 5 was Gravity, which pulled in another $13.1 million in its fifth weekend. Warner Bros.’ $100 million space drama starring Sandra Bullock and George Clooney has now earned $219.1 million total and, with a little awards attention, should ultimately hit about $250 million domestically. 
 
 1. Ender’s Game – $28 million 
 
 2. Jackass Presents: Bad Grandpa – $20.5 million 
 
 3. Last Vegas – $16.5 million 
 
 4. Free Birds – $16.2 million 
 
 5. Gravity – $13.1 million 
 
 Outside the Top 5, 12 Years A Slave continued its successful expansion this weekend. The Oscar contender jumped from 123 theaters into 410 locations and pulled in $4.6 million as a result. That gave the film an excellent $11,220 venue average, thus assuring it will continue to expand into more markets in the near future. Fox Searchlight could have a sleeper hit on their hands. 
 
 On the international front, Thor: The Dark World hammered up a great debut this weekend. The film pulled in $109.4 million from 36 territories, which represents about 70 percent of the international market. The film performed best in the United Kingdom ($13.4 million), France ($9.4 million), and Mexico ($8.2 million), and it still has openings in China and Japan to look forward to. The original Thor grossed $268.3 million internationally in 2011, but after a major exposure-boost from The Avengers, The Dark World seems poised to easily outdo that film’s overall performance. It opens in the U.S. on Friday.
– Futuristic flick Ender's Game played its way to the top this weekend, though its $28 million isn't much to cheer about for Summit Entertainment, the Los Angeles Times reports; Ender aims to lead a new teen franchise, the Hollywood Reporter notes. In second place was the still-sprightly Bad Grandpa from prankster Johnny Knoxville, with $20.5 million, just a 36% drop from opening last week. Last Vegas, which sees the likes of Morgan Freeman and Robert DeNiro headed to a bachelor party, rolled a three with $16.5 million. And flying into fourth place was the 3D-animated Thanksgiving feature Free Birds. Gravity, meanwhile, landed in fifth, with $13.1 million, Entertainment Weekly reports.