Let me describe to you my first encounter with Space Alert:
"Hey Greg, I've got this new game called Space Alert, want to play?" "Sure, but I've got work tomorrow so I can't stay later than ten." "That's okay, this takes less than an hour for a round."
"We finally won a mission, now we get to record experience points on our character that let us start the scenario with differently abilities to normal."
"That time we didn't take any damage, that's an achievement, bonus XP"
"I can leave a little later, stopping on a losing streak would be a little rubbish."
"Wow, so you get an achievement for winning without taking any sort of positive action in a third of the rounds...hey, is that why we lost two missions before this one?"
"Oops, I missed the last bus. Hey there's an achievement for starting a game before midnight that finishes after midnight. Quick, hit start before it's midnight!"
"So...tired. Lets go to be...oh, there's an achievement for winning enough games in a single sitting, we'd only need to win one more."
Strictly what I'm describing is an encounter with Space Alert's expansion, which added the experience and achievement system. The theme is that your particular officer is going on several missions and can accumulate experience over several missions to obtain bonuses. Mechanically these replace an existing bonus (If you play with the expansion you no longer draw a special gold card) and aren't substantially more powerful, but they are cooler. Being able to fire a laser for +1 damage is useful, but being able to jump to the top of the turn order, sprint into a room and stick the gunner full of combat drugs so that she can fire for +1 damage makes you feel like more of a badass - An' that's just the medic! A class famed for its passive nature. Other classes let you do more active things such as duct taping two rockets together and pushing them into the launch tube at once in the hope of doing more damage.
It doesn't seem very common for games to have achievement systems, though I've come across examples where it isn't a major part of gameplay. I think it's a shame since the Space Alert system adds so much to the game, but then I realised a lot of people already play some games as if they had such a system. How many of you have had the experience where a player gets the opportunity to do a move that's rarely available or produces some very unusual result and decides to pursue it rather than trying to win? I know I have countless times and I know I've got a tendency to try to force a win using the most unlikely condition, or the weakest piece on the board or the most rarely used special rule, just to see if I can. Sometimes, I just do things.
Reflecting on it, I think that some games encourage this more than others. Take Helix Pinnacle, this is a Magic: The Gathering card that allows you to spend one hundred mana over the course of several turns to win the game. It is extremely rare that this is a serious option, as there are so many ways to win the game in less than a hundred mana that aren't so fragile that your opponent might find a way to remove all of your progress once you've spent ninety-nine. It's an achievement by the backdoor, a challenge for players like me. It's not a card that says "Here's a competitive way to win the game", it says "I bet you can't achieve a win this way". I think in their own way a lot of games have something equivalent, that encourages games to play them differently seeking an achievement rather than playing efficiently for a straight up win.
A quick aside: my all time favoriate example of this is in Dune. The Bene Gesserit player writes down a player and a number at the start of the game, if that player wins on that turn you win instead. I find that so tempting as a goal I find it almost impossible to try to play for any other type of win.
Where was I? Achievements! Achievements have added a lot of joy to games I've played and I think that they're present in the design of a lot of games that might not formally acknowledge their existence. I'd like to do the same thing in the games that I design, either formally or informally. This leads me to thinking about what makes a good achievement; I think it comes down to two things:
A good achievement rewards the player in some way, that's not more powerful than ignoring the achievement system. In Space Alert this is a card that gives a player an interesting ability, rather than a powerful one. In Magic, it's a win that could have been obtained more easily another way. In Dune it's still a win, but with the added bonus supplied by the look on your opponents face.
The second thing it needs to do is to change the way you play. "Win by a big margin" isn't an achievement that adds anything to a game. You were already trying to play well; the existence of the achievement isn't going to lead to a new play experience. It doesn't require a novel strategy or suggest a different approach, it won't add to the games replayability by pushing you to engage with it in a different way. An achievement needs to be something like "Win using limited actions." or "Win by trying to force another player to win on a particular turn." or "Win using this particular sub-par option you'll have to find means to support" - those can really add something to a game.
I'd love to promise that there'll be such a system in my first game, but they could take a lot of time away from testing, balancing and improving the core gameplay. There's probably a reason that it was the space alert expansion rather than the original game that contained these achievements. I would really like to do it, I just don't know if there'll be time. At the very least, I'll make sure to include at least a few deliberately sub-par or unlikely options for players to pursue.
Such as killing the target by possessing his bodyguard in assassins, saving the day by entombing yourself and a demon in ice during a round of wizard academy or trying to defeat the director in murder TV by hitting his soldier with a bomb on a stick and hoping it explodes killing him and not quite you. All of which are examples of things that have happened in playtests so far!