A key prerequisite to effectively accommodate the particularly broad spectrum of diverse interaction requirements imposed by UA-Games is to firstly design the interactive game space at an abstract level, in a representation-independent way, eliminating all references to the physical-level of interaction (e.g. input / output devices, rendering, low-level dialogue). Once this is accomplished, the next step is to appropriately capture the lower-level design details, incrementally specializing towards the physical level of interaction by addressing particular user characteristics.
To this end, a design approach capable to represent an open set of alternative physical designs under a common abstract design umbrella is the Unified Design method (Savidis & Stephanidis, 2004). This method reflects a process-oriented discipline emphasizing abstract task definition with incremental polymorphic physical specialization.
The basic steps in applying Unified Design to the development of UA-Games are summarised in Figure 1 (below). As shown, Unified Design is a highly participatory, user-centred, iterative process, since:
Quite often, in order to evaluate the decisions made at a specific step, or to weigh alternatives before committing to them, it is required to quickly create small-scale temporary prototypes, known as “throwaway” prototypes. These may range from rough hand-made sketches to simple programs. Prototyping is an essential part of the iterative design process since it provides a low cost, tangible means for gathering early and meaningful user feedback, and, at a later stage, can also serve as a common reference point, as well as a concrete, unambiguous, documentation medium for communicating design specifications to game programmers.
At this point, it should be noted that game programmers are also involved in the whole process with a two-fold role: (a) they provide input about technical requirements and restrictions, as well as about the feasibility and cost of alternative design solutions, and (b) they develop and “tweak” the required electronic prototypes.