Game/Series: Mass Effect
What it did right: Made you care about your team
Mass Effect is well known for allowing you to make decisions, some big and some small. This had a massive effect on your personal feeling towards the characters in the game.
Remember trying to save Wrex, if you failed he died and how heartbreaking that was? Remember losing Ash/Kayden? Remember watching Thane die? Remember how happy, and slightly creeped out, you were when EDI and Joker announced their love for each other?
Mass Effect had an amazing way of making you care about who lives and who dies, by letting you interact and chat to these characters, this created a strong attachment to them.
Image credit goes to LevelSave.com
Game/Series: Grand Theft Auto 4/5
What it did right: Made the world feel alive.
If you just wait in your car, or stand by the side of a road, for a while and at some point two cars will crash into each other. The drivers then get our of their cars and start to fight. One of the drivers wins, but due to a police officer being close this man gets arrested. An ambulance then appears later to help the guy who was beaten up.
If you have your gun out, many people will run away, screaming, but not everyone. In some neighborhoods, if you stay in them for too long you might attract unwanted attention, and maybe a few bullets.
The world of GTA 5 feels alive, and I don't think I have seen a degree of humanity to this level in games before. Which is also why the AI in this game get's a notable mention on slide 4.
Game/Series: The Elder Scrolls (TES)/Fallout
What it did right: Massive open world, ripe to explore.
Both TES and Fallout have always been known for their massive open worlds; you can go anywhere, do anything, be anyone. Skyrim and Fallout 3 did this the best, in their respective genres, allowing you the become whoever you want. Explore the world at your own pace, and in whatever way you like. Want to ride a horse? Work, and then buy one first. Walk or run everywhere - defend yourself or flee. Go to any level of area whenever you want and take your chances. The choice is yours.
Notable mention: Just Cause 2 - Even thought it didn't allow for a choice of who you will be, exploring the islands of Panau is great fun, and beautiful.
Game/Series: Interstellar Marines
What it did right: Some great AI
The AI will react to flashlights, laser pointers, and gunfire. If you see a flashlight they will run towards it. They will flank you, and sometimes rush you when they have outnumbering forces. They can open doors, which sometimes allows for some dual breaches, and you now have enemies in front and behind you. While this AI is not groundbreaking, smart AI is something which more games should strive towards, and for an indie game to do this well it's nothing short of amazing!
Notable mentions: Max Payne 3, Metal Gear Solid V: Ground Zeroes, Grand Theft Auto V.
Game/Series: Portal Series
What it did right: Puzzles that made you think, but where never impossibly hard.
You start off playing Portal with no gun. This allows you to learn that you can step through Portals to transport yourself places. When you are given the portal gun, you only can fire one colour of portal, this teaches you that you can go into either end of the portals. Then the complexity builds until the game allows you to experiment with some more freedom, until you are whizzing through physics-based jump puzzles.
Portal also made you think, not just with the puzzles, but about what it would be like to have an AI as smart as GLaDOS. Is this portal gun possible? Would having a portal gun mean I no longer have to move to get to the fridge? If so, how lazy can I be? How lazy would you be?
I'd be VERY lazy.
Notable mentions: The Talos Principle, Q.U.B.E, Quantum Conundrum