I wrote a 50,000-word module for Gary Gygax's Castle Zagyg: Yggsburgh that never saw the light of day, because his widow cancelled all his creative works and that of his developers. In that module, The Grand Temple and College District, I created some loose guidelines for an alchemist class, designed for the C&C game. In case you are curious, here is what I came up with back in Late 2005 / Early 2006:
APPENDIX D: Alchemist Class
The alchemist should be considered an NPC Class, for it is not their wont to venture from the laboratory, but in the rare instance that a player should express a desire to play one of these characters, the following guidelines are suggested:
Alchemists may be considered a sub-class of the wizard or illusionist. They share the same hit dice, weapon restrictions, armor restrictions, experience point progression, and the ability to cast spells. However, the alchemist can not begin casting spells until fourth level and will remain three levels less in ability throughout his or her respective career. The alchemist can, however, brew all manner of potions, including arcane and divine. In this capacity, they function as though they were three levels higher, as per the rules presented in Monsters & Treasure. Thus, a fourth level alchemist can begin brewing arcane potions and a sixth level alchemist can begin brewing divine potions. All other rules presented in said volume apply.
The alchemist brews ambrosias, balms, elixirs, philters, potions, salves, simples, tonics, unguents, and more. The alchemist becomes an expert with herbs and ingredients magical and mundane, and where in nature the these ingredients are derived. He spends the bulk of his life cooped up in the lab and lives a very sedentary life, and as such may suffer poor constitution over time, but such is the sacrifice for his craft. He can not perform his craft on the road adventuring! He needs access to his lab which contains a fireplace, workbench, brazier, bellows, an analysis kit, and dozens of alembics, apothecary jars, beakers, flasks, dishes, mortar and pestle, retorts, and vials. Without access to these, he is no more than a deficient mage.
The alchemist researches using formulae of a complex and arcane sort that no other class can read. He delves in the research of metal, stone, and gems and the magical properties thereof, including reactions to activators and inhibitors in the creation of alchemical mixtures. He works with all manner of flora, including ferns, fungi, grasses, herbs, moss, shrubs, trees, vines, weeds. For an in-depth treatment of all these mineral and organic ingredients and their associated functions both magical and mundane, please refer to Gary Gygax's World Builder by Gary Gygax and Dan Cross.
HYPERBOREA- A Role-Playing Game of Swords, Sorcery, and Weird Science-Fantasy