15 Year-old son has used size markers as toys since he was eight

I apologize for the long post, but I feel the topic needs a fair amount of backstory. (I'd appreciate it if you read through everything, but there's a TL;DR at the bottom :) no worries regardless)​My son - now fifteen - has had this near life-long thing where he uses objects to stage battles. Initially, he used stuffed toys and built elaborate 'space ships' out of pillows, cardboard boxes and blankets. His stuffed animals would be his crew, and he would play out some sort of mission or fight.This started at around 6 and continued until he was 12. I know it's quite standard for a lot of parents, but it gets more elaborate. When he was eight, we went to a clothing superstore that utilized those Mark Bric size markers. The sheer amount of people that passed through the aisles every day meant that the floors were liberally littered with plastic things.Every now and then, I would see my son pick one up and fiddle with it, but I thought nothing of it. Overall, I saw him pick up maybe five or six, but some months later, it turned out he had been collecting them over multiple trips, and had nearly 200 of them stashed in his room.We considered returning these as they were technically stolen, but they're mass produced and literally cost around one cent each, so we decided to let it go.In my son's defense though, he did put them to good use. Seven years later, he still has the size markers, and still uses them regularly as 'soldiers.' Basically, he began to use each size marker as a person, and started to stage battles with them. Initially, we were concerned, since we're fairly against violence, especially at the age he started making these simulated battles (eight, as mentioned previously).But we watched him, and eventually we decided to let him play. As my husband began playing along with him, we realized that he had built up a surprisingly intricate world with the size markers. He easily had (has) two dozen of the more uniquely shaped and colored markers with set names and personalities. He has entire histories played out with them, to the point that he refused to play out battles between the white and red markers, as they had always been 'allies' since the start, and it 'felt wrong/didn't feel right' to mess up that history.Our main concern was that this was his primary source of entertainment - LEGOs and other toys were mostly disregarded. As he got older, the battles he staged became more elaborate, and grew to include other random bits of plastic and cardboard that he used to construct settings, or that he used as boats or cars, etc (Lids and containers are typically ships and buildings, respectively).For some reason, he always seemed to prefer these made-up entities, for lack of a better word, than anything else. The size markers and lids are very obviously not ships and soldiers, but more visually realistic things like LEGOs never held appeal for him, for some reason.A few weeks ago, he enrolled in a woodworking shop and got his hands on some scrap wood and a laser cutter. I kid you not when I'm saying that he cut out an even 800 wooden circles, took them back home, split them into eight even 'factions' and colored them with different colors. He now uses these along with the Mark Bric size markers to stage even more massive battles, and at fifteen, its beginning to get unusual.TL;DR, my now 15 year-old has used Mark Bric size markers as toys since he was eight, and often stages elaborate battles with intricate background histories with them. Recently he used a laser cutter to make 800 wooden lookalikes of the size markers and is currently engaged with that.My question boils to down to whether any of you other parents have seen this sort of thing in your children (though perhaps not to this extent). Additionally, should I be worried that he still playing into his teenage years? via /r/Parenting https://ift.tt/2zHjsuu