It was little over a decade ago when the MCU kicked off with Phase 1. With the first Iron Man film, these movies teased the potential of a larger connected universe where some of our favorite comic book heroes might meet and share the screen. Few people thought that such a bold idea could be pulled off or that Marvel was even going to really attempt it at all. With Marvel’s Phase 3 now wrapped up, it seems clear this was a gamble that paid off.

Phase 1 was a smaller part of the bigger picture but an extremely important one. With only six films, the first Phase was responsible for introducing some of the biggest and riskiest franchises at the time. It wasn’t all smooth sailing but the result was a group of movies that helped launch the MCU. Here are all Phase 1 films ranked, according to Rotten Tomatoes.

The Incredible Hulk (67%)

The Incredible Hulk was the second attempt to bring the character to the big screen following the Ang Lee-directed Hulk from 2003. This new film starred Edward Norton as Bruce Banner who was on the run from the military attempting to find a cure and control the monster within himself.

This movie is sort of the forgotten child of the MCU. Norton bailed from the MCU after this, which resulted in much of the continuity ignoring that it existed aside from General Ross’ appearances. It didn’t help that critics didn’t fall in love with the movie either. Though some enjoyed the action-heavy adventure compared to Lee’s version, the overwhelming CGI and bland performances made it pretty forgettable.

Iron Man 2 (73%)

Iron Man was the first proven success for the MCU and the film that seemed to help convince them that this insane plan of theirs might actually work. It’s not surprising then that a sequel was fast-tracked, making it the only franchise to have two films in the same phase of the MCU.

In another early bit of recasting, Don Cheadle took over for Terrence Howard and officially became War Machine. The movie also added Sam Rockwell and Mickey Rourke as villains in the tale of Tony Stark becoming more reckless as Iron Man while confronting his past.

The sequel was a letdown for many critics who were quick to note that this was not the breath of fresh air that the first film was. Still, some of the inventive action sequences were praised while they admitted Robert Downey Jr. was still hugely entertaining in the lead role.

Thor (77%)

There were a lot of uncertainties going into Phase 1, but surely one of the biggest question marks was Thor. The character is so different from the other Earth-bound characters and even his origin meant the MCU would have to introduce a large fantasy element early on.

The first Thor film was directed by Kenneth Branagh and introduced Chris Hemsworth as the God of Thunder. The film finds Thor banished to Earth where he met Jane Foster (Natalie Portman) and tried to prove his worthiness while his brother Loki (Tom Hiddleston) took the throne of Asgard.

Critics weren’t thrilled with the tacked-on love story and were surprised by the small-scale story, but many thought it was a fun adventure for a unique hero. They pointed specifically to the humor as a major highlight while Hemsworth and Hiddleston were noted as promising newcomers.

Captain America: The First Avenger (80%)

Captain America could have easily come off as the corniest character ever, but the MCU managed to introduce him in a way that made him instantly likable and appropriately heroic. Set in the 1940s, Captain America: The First Avenger told the story of skinny Steve Rogers who became a super soldier in order to fight for his country in World War II.

Critics noted that the character is still a bit hard to take seriously, but there was plenty to like in this pulpy throwback. They seemed to enjoy the period setting and retro vibe of the film. Chris Evans’ debut as the hero was also pointed at as a selling point for the character. Praise for the film has seemed to have increased over time but even during its initial release, critics agreed the old-school adventure was the right way to introduce this character.

The Avengers (92%)

The entire Phase 1 culminated in this massive movie which saw all the heroes coming together to form The Avengers. As Loki enacts his plan to conquer Earth, Nick Fury calls upon the world’s mightiest heroes to come together and save the day. Of course, they needed to get past their own massive egos and infighting first. Marvel brought in Joss Whedon to direct while Mark Ruffalo replaced Edward Norton as Hulk.

If it had not worked, the MCU probably would have ended right there. However, the movie became a huge success, not just with audiences but with critics as well. The majority of critics were amazed at how the film balanced all these characters and found satisfying ways for them to interact. The cast worked extremely well together, the action was thrilling and the movie was surprisingly hilarious. The overwhelmingly positive response helped the MCU go forward to bold new places.

Iron Man (93%)

It all started with this second-tier superhero that few moviegoers even knew existed. The first film in the MCU told the story of Tony Stark, a billionaire weapons developer who is captured by a terrorist group and builds a suit of armor to escape. He then learns he has a bigger responsibility to the world and becomes Iron Man.

Even forgetting about the lack of enthusiasm for the character of Iron Man, the film was not a surefire hit on paper. Jon Favreau had never directed an action movie. Robert Downey Jr. was a highly controversial figure at the time. And filming started without a script. Somehow, those uncertain aspects came together to create something truly special.

The movie was a huge hit with critics who described Iron Man as perfect popcorn entertainment. The humor and action helped give the film a real sense of energy, the suit designs were thrilling, and the cast was fantastic. But the real praise was reserved for Downey Jr. who became instantly iconic in and outside the role of Tony Stark.