i dont have the 2005/2004 clients but after being absesd for a month i think i know how they work. so it seems you could have the option to make a level with a robloxian or be 3d persone like in roblox studio. there seems to be no health bar so my guss is that you die realy easily. there were contest and how they would work is that you have a time limit and you would have to finish it before you run out of time and the one that did the best in points wins. there was a score bored at the side of the site with the top 10 players. the contest would be anoueced int the front page. one example of a time limit and no health bar (you die instintly) is this game
Junkyard Wars! This is a build and then drive game. You have 2.5 minutes to destroy the four alien robots. Their yellow "brains" will kill you if you touch them, even after they are destroyed. Use blocks and the three different spawn guns to build up your "weapons chassis" and then go hunt the bots!
I'm in the ROBLOX client search Discord channel, and I recently found this forum. I wasn't the one who found this, but no one has posted it here so far so I decided to:
Someone recently found a installer .exe from December 2007. It would install the 0.3.676 version, which is from the end of December 2007.
Seems like there's no files or anything linked to it because it gets them online similiar to the Roblox.msi from January 2007, but I decided it was worth posting here anyway. You can get it here: gamefront.online/files/9388278/Roblox_Setup.exe (credit goes to OPisMoney on the Discord for finding it)
Also, I recently found a lot of file version numbers (0.3.xxx.0) from late 2006 to mid-2008. Not sure how helpful these are, but I don't think anyone else has found them before, and they might be helpful at some point.