Agile game dev (3/5) - Keith 2010

Agile game development with Scrum, Clinton Keith, 2010

Part III - Agile game dev

Read the series: 1/5, 2/5, 3/5, 4/5, and 5/5.

Video game project planning

The minimum required feature set are the must-have stories. For an FPS, they may be: 8-12 hours of story, shipping for Christmas, advanced NPC AI, or online gameplay.

Publishers require early concepts.

Any game development has the following 4 phases. During the concept phase, ideas are generated iteratively until the green light of the publisher. In pre-prod, typical levels and assets are created iteratively to estimate the value of the minimum feature set (which mechanics are fun, which artistic themes are interesting) and cost (hours, license fees, skills, or technology). Production relies on the knowledge acquired during pre-prod to build, at the lowest cost, the 8-12 hours of content. Production is pipelined, ie mass-produced like in a Ford factory. Post-production deals with polishing.

The production debt is the amount of work that needs to be done in production right after going out of pre-prod.

Production is assembly-line work/pipeline, there should be no starvation. This pipeline model does not fit well with the sprint model: imagine a sprint centered on a particular theme such as a dragon boss. Modelers in the team would spend the first week making the model, then animators would spend the next week animating it, but modelers would have no work to do. Each specialty end up working only a fraction of the sprint - this is not good.

Solution: lean practices, and more particularly a Kanban board. In a Kanban board, tasks flow from the left-most column to the right-most column as they progress throughout the pipeline. To pipeline the creation of characters, each discipline (e.g. modeling) should pass a task to the next discipline (e.g. animation) on its right on the Kanban board every week. Much like any assembly line, when being part of a prod pipeline, the developer can only spend a limited time on a task, otherwise he will slow everyone down.

But some tasks take more time than others. For instance, it has been estimated that it takes 2 weeks to complete the modeling of a character, 3 weeks for the animation, and 1 week to add the character's audio effects. So the character asset ideally spends a total of 6 weeks in the pipeline. This is called the cycle time, although definitions differ. But once the pipeline has been filled, a character is done every week. This is called the takt time, or production rate. In our example, to reach a takt time of 1 week, the team should have 2 modelers, 3 animators, and 1 sound effects engineer. To prevent starvation, task buffers between columns can be put in place, but they increase the cycle time (because tasks end up spending a couple extra weeks in the buffer columns).

Teams

Teams are usually cross-disciplinary (e.g. 2 designers, 3 programmers, 2 graphics artists, and 1 sound artist), self-managed, and self-organized. Yet the lead developers manage planning and resource allocation. They also mentor and review the team members so that they can improve their practices.

Working 100% on a few features is better than working 25% on many because it gives a sense of accomplishment. But it is not always possible (e.g. when 4 teams share an audio effects engineer).

Shared infrastructure teams provide low-level support that multiple games rely on. They are not always cross-disciplinary. For instance, the team working on the foundation of the engine may be entirely composed of engineers. Such teams should keep in mind their users: most of the time, they are other developers. These teams have their own product backlog, sometimes longer sprints taking into account in-house support and maintenance, and their product owner should be an exec (e.g. the CTO for the engine team).

Meeting-wise, scaling Scrum happens during the Scrum of Scrums. This meeting is attended by 1-3 members from each team, and is moderated by one of the scrum masters. Mike Cohn gives advice on the agenda and frequency of this meeting, but it's usually weekly or bi-weekly. The goal is to discuss a backlog of shared impediments, and eventually trade specialists such as a mo-cap technician between teams. Specialist-swapping requires some planning to avoid overlapping demands between teams. Another way to approach specialists consists of having them stay in their team, but dedicate only one half of their task points to their team, and the other half to support/advise other teams.

Vision-wise, if there are too many teams for 1 owner, then there should be a lead owner and a few owners, each in charge of a domain such as UI or AI. The owners should meet frequently to keep their vision in sync.

If the sprint dates of 5 or more teams coincide, then a single owner can not attend the sprint review meeting of all the teams. Pros: teams can swap members and gain a more holistic view of the build. Con: there must be an additional owner, risk of diluted vision.

Communities of practice gather developers from the same discipline, such as graphics or AI. Those meetings happen weekly or bi-weekly. In those meetings, developers share progress and information to avoid duplication of effort. For instance, no 2 teams should have their AI engineers develop their own engine on their side: they should first talk about it in their community of practice to see if other teams have coded the engine already.

Read online the chapter about teams.

Faster iterations

Development iterations suffer from overheads such as compilation, delays to propagate the tuning of a variable (need to recompile the whole game to change the HP of 1 monster), asset baking (transforming objects from the format they were created in to a format that the platform can import directly into the game), bug fixing, or administrative issues. Agile aims at reducing this overhead, as measured by automated baking/compiling tools, and plot it every day to see if changes are effective. Solutions to reduce iteration time include fixing bugs, improving asset creation tools, upgrading development machines, or being able to hot-load assets or edit parameters in game.

Tests: With small commits, the team can find which commit introduced bugs by running tests. Much like the increasingly demanding definitions of "done", there are increasingly demanding test strategies. Continuous testing happens at the order of the minute, and includes: the build compiles, passes unit tests, and passes asset validations. Hourly tests include passing platform smoke-tests (loads and starts running) or loading a level without crash. Daily tests include running a scripted bot play-through, or a QA play-through. QA can play through the daily build twice a day for 30 min. Everyone understands the stability and of a build by its file name and date: "MyGame_20120727_smoke".

Assets should be compressed when transferred between SVN repos. If bandwidth becomes limiting, either pre-transfer builds and assets overnight to those who need them, or buy more bandwidth!

Read more:

• Poppendieck 2006, Implementing lean software development
• Ladas 2009, Scrumban
• Larman 2009, Scaling lean and agile
• Crispin 2009, Agile testing
• Lakos 1996, Large-scale C++ software design