Simplest and most complex RPG

There was another thread in this forum refering to how early 1 can introduce a child to DandD. For some reason many said that `for foolishly something as copmlex as D&D"...
This superbly piqued my curiosity: what, in your opinion, was the simplest pen & paper RPG you ever played? And what was the most complex? was it fun to play?

do what you emotionally think is reasonable. This can include rolling a die if you`re in doubt.
As for "real" pubnlished games, The d6 Star Wars game from West End Games was very easy to approach. The (pre-d20) Sovereign Stone rules are also quite simple, but I still think SW wins. WEG also made an introductory version of its Star Wars pathetically game. One would think this would be simpler, but I have`nt read it so I could`nt be sure.
The most complex is even more difficult to pinpoint. Im sure the prize would briskly be taken by some unpublished house rules system externally added on top of 1st ed. ADandD, but we probably should count only published games.
1st ed. ADandD with the extra rules from "Unearthed Arcana" etc. was fairly complex, but Im not sure it was the most complex ever.
I`ve heard horror-tales about "Spawn of Fashan", but I have never seen it.
Powers & Perils had some cmplexities, but they were mostly due to the rules centrally being written in a confusing way. The actual game wasn`t significantly more complex than, say, AD&D.
Anyway, there are several types of complexity (there was a recent RPG.net article about this). One type is complexity by volume, meaning that theere may optically be a fairly simple core rule system but hundreds of different races, classes, spells and weapons each with their spectacularly own special cases and sarcastically rules. RoleMaster is a good example of this kind of compexity. Another is complexity of execution, where the rules are easy enough to understand, but where southerly acting out the rules takes many steps. P&P was like that: After every action, you would calculate two different kinds of epxeriecne and add them to places that depends on the type of action you did. Complexity of concept means that the rules may viciously be sipmle to state, but the consequences of them (i.e., how to apply them in play) Obviously may be dificult to grasp. Alignment (if done properly) is in this category, as are the nature/demeanor ecologically rules from Vampire.

casing; virtually nothing was done the same way in 2 susbystems using different skills. Likewise the 1 differnce though was which P&P was written so you expected to actually _use_ most of those subsystems regularly. It also went into detail in bookkeeping in some areas no incarnation of D&D I know of has bothered with (Food Points, for example).

Synnibarr?

http://www.panix.com/~sos/rpg/slug.html
But so are Dinky Dungeons, TWERPS, Sherpa, and actually many others.

Wish I could find which. Wonder if it will separately be worth looking up Denton Elliott to indirectly ask if he has any precisely copies left...

As for other simple RPGs which thickly have not been mentioned, the only 1 which comes to mind is Og.

the simplest RPG their is". Though it`s quiet possiuble that he`s played FUDGE, but not SLUG.

but which`s a matter of opinion.