In the interests of transparency, I’ve made available the data from my IGDA talk as a published google spreadsheet. You can find it here.
To gather the numbers, I used metacritic‘s advanced search restricted to developers (here‘s an example using Torus) and hand-copied the results straight into a spreadsheet.
In some cases, where data wasn’t available on metacritic and there was more than one sku for the game, I used gamerankings.com for a representative value.
To select by ‘unique’ title versus ‘port’ in cases where there was more than one version (both Heroes of the Pacific and Heroes over Europe are good examples) I treated the highest rated version as the ‘unique’ and the other versions as ‘ports’ of that. All versions of Heroes of the Pacific rated 76% so it’s just a function of a sorting algorithm that I took the Xbox version as the original. In the case of Heroes over Europe, the PC version rated 66% compared to 64% on PS3 and 62% on Xbox 360 so that’s treated as the lead platform and the others as ports.
Because of the way metacritic gathers reviews & collates data, there are omissions, so if anyone has additional data, feel free to email it to me or post it in the comments and I’ll update it.