Here's a piece that I originally did for the 1st Editions Advanced Dungeons and Dragons "clone" Old School Reference Index Compilation or OSRIC for short. I did a lot of art for the 2.0 release of the game. The 1st edition wasn't meant to be a stand alone game, more of a way small publishers could release new material for 1st edition AD&D legally without running afoul of the copyright laws.
It became apparent that people were eager for more 1st edition goodness so Stuart Marshall took the reigns over from Matthew Finch to put out a fully realized clone of the 1st edition rules while avoiding the copyrighted material. The result was OSRIC 2.0, a combine effort of the folks over at the Knights and Knaves Alehouse forums under the guiding eye of Stuart Marshall. I was a somewhat regular of the forums at the time and had a few publishing credits for a 3rd edition D&D company, and was eager to get back to my roots of old school gaming. I di quite a few pieces of art for the 2.0 version of OSRIC and had quite a lot of fun with that. Even though the work was unpaid, it did cement my "career" as an illustrator which has been going for over 15+ years now. I've had a lot of fun contributing to the hobby. Indeed, this past year has been one of my busiest yet with work for Skeeter Green Productions, Expeditious Retreat Press, Dungeoneer Guild Games, Northwind Adventures, and more.
At any rate, if you are curious about old school gaming, here a link to the OSRIC 2.0 rules (got get them, they're FREE!): http://knights-n-knaves.com/osric/
Also, if you are wondering how old school games differ and the mindset of how they are played, Matthew Finch wrote an excellent primer on old school gaming: https://www.lulu.com/shop/matthew-finch/quick-primer-for-old-school-gaming/ebook/product-3159558.html?page=1&pageSize=4
And finally, I tantalize you with a very short site encounter for old school gaming that was part of the Sea of O'Sr shared world some time back. Enjoy and happy gaming!