GAME SYSTEMS DIDN'T WORK AS INTENDED
A third area that influenced the changing nature of the game's design was when the game systems didn't work as we intended them to. High-level concepts imply gameplay but don't -- and can't -- define it. We quickly found that descriptions of game systems are no substitute for prototypes and actual implementation. We prototyped every game system, as documented, relatively early on. We built some test missions, not quite early-on-enough but still early.
These test systems and missions revealed gaping holes in our thinking or things that we thought would be true that turned out not to be true at all. For instance, our augmentation and skill systems proved dry and rather dull, once implemented, despite looking really good on paper. Those systems were designed around the totally valid idea that the computer would resolve actions without any secret (or even non-so-secret) die rolls required. Players would always know, with absolute certainty, based on their character development choices, whether they could accomplish something or not. The trick would be whether they wanted to do something or not, based on an assessment of the likely outcome and the likely consequences (for example, blowing down a door and setting off alarms versus the risk of picking a lock and being caught while doing it). In addition, I thought the tension of standing outside a locked door, not knowing if a guard was going to show up while you picked the lock would provide sufficient excitement. I thought knowing you could leap across a chasm because you had the Jump augmentation at Tech Level 3, opening up new paths through maps that were inaccessible to players without that augmentation, would be good enough to keep players interested.
When Gabe Newell from Valve came down and played our prototype missions, he correctly identified the utter lack of tension in our skill and augmentation use, as written up in the design doc and ably implemented by the coders. The worst was confirmed when Marc LeBlanc, Doug Church, Rob Fermier, and other friends from Looking Glass Studios and Irrational Games played the proto-missions and came to the same conclusions. Actually using skills and augmentations revealed things that merely thinking about them could never have revealed.
We took the criticism, and with it in mind, lead designer Harvey Smith revised the skill and augmentation systems pretty thoroughly, proposing an elegant system of consumable resources and time passage, all tied to skill level. This increased the tension level, provided new rewards, and allowed players to think and make informed decisions. Harvey also proposed a revision to the augmentation system, introducing an energy cost for their use (something I had foolishly rejected earlier on). Again, this gave us the opportunity to hand out items that would replenish energy -- in other words, we instantly had more things to hand out to players as rewards. It also introduced a level of tactical thinking to augmentation use that makes the system work. None of this would have happened without prototype missions and some harsh (but fair) criticism they allowed.