The Generic RolePlaying Game Aid (GRPGA) is an interface to allow you to play your game system on Foundry VTT.
Currently supported systems are D20 (DnD3.5, World of Warcraft and Star Wars), 3D6 (A generic system where you roll 3d6 less than a modified target number) and a D100 system for Against the Darkmaster (VsD), now with Spanish localisation. Support is in beta for a D20 derivative using 3d6, (Ops and Tactics System), and D100 support for the RoleMaster family of games (RM/SM, MERP, HARP) [WIP but progressing :-) ]. A more feature-rich ruleset has been added to handle the various flavours of Palladium games and a system-setting hi-jack of the Palladium ruleset supports D6 Pool games like Shadowrun 4E and another is in progress to support Aternity RPG. Another system-setting hi-jack of the Palladium ruleset supports Percentile, D20, 2D10 and 3D6. Work has begun on a ruleset for the Fragged family of games.
GRPGAs strength is that it is almost completely item-based so you can create just about any type of thing you need but you also need to create just about everything you need (with some notable exceptions).
There is simple import capability for both D20 and VsD baddies in a commonly-used stat block format that results in a static actor with most features and abilities precalculated so the modifiers do not appear when the ability is rolled. There is a more developed import ability for 3D6 actors which involves using GCS to output your character in a specific format, which you then import into GRPGA. Further work on imports into more recent rulesets allows updating of existing items rather than importing again.
GRPGA is not intended to replace your character sheet (but comes pretty close in most cases) but instead provide quick access to any features that require you to make a roll with context or just for you to share information in Chat, as well as anything you need to keep track of like consumables or ablatives. The flexibility of the Modifier item type is such that you can create modifiers for any situation or condition and have them listed and calculated when you make a roll. This allows players and GMs to verify that all appropriate modifiers were applied to the base roll.