Before we begin: trolling this thread with comments about how certain custom settings diminish the game are not wanted. That may be your opinion, but personally I think trying out new stuff is fun too. I still mainly play games with normal settings, but something like this from time to time is great fun.
So, in the past whenever I've played custom matches where everyone starts filthy rich and level 20, I've thought that a hell of a lot of strategy was left out and it was just a boxing match with little else to it. Today, I played several good games like this, though, and realized that this can be an exceptionally fun way to play when the teams are well matched in skill. Here are the settings we played with earlier, and it makes for a compelling and fast paced match:
Slaughter - 40 kills
Starting Level 20
Filthy Rich
Fast Gold
Strong Towers
Strong Grunts (this, in particular, is interesting... and makes getting giants an even bigger deal)
Light Death Penalty
War Score 1 (the normal setting, with normal rank gaining speed as well)
Normal Flag Capture Time
Normal game speed
Usually when people set up games like this, towers and grunts are normal strength and therefore are completely unimportant. with the strong setting, they actually matter a little bit at two points: (1) getting priests is no longer a bad thing, and now they actually change the tide of the game if someone gets them significantly earlier and (2) a full wave with giants is even harder to kill.
So, here's what the game ends up being about (and note that all of this actually tells you a fair deal about managing strategy in this game mode).
(1) Shopping deprivation. Everyone starts with 25000 gold, so everyone wants to spend it on an artifact or two right out of the box. What this means is that everyone needs to rush the artifact flag immediately, usually without even choosing their skills yet. First team to cap and lock it gets their artifacts and at least 45 seconds of preventing the opposing team from getting effective equipment. A large part of the game revolves around preventing your enemy from shopping when they want to -- so even after the initial rush you'll try to hold it as long as you can, and again as frequently as you can for the rest of the game. This is probably the single most important strategy in this game mode.
(2) Getting priests. A 1v1 boxing match between demigods in this mode often means you're gaining health at the same rate you're losing it (or close to it) thanks to hp regen and life steal items. If one side has priests and the other doesn't, they consistently win until the other side catches up.
(3) Holding flags that give combat-relevant bonuses now matters more. Of course it matters in the regular game, but since everyone is hitting twice as hard and three times as fast, these flags really mean a hell of a lot more.
(4) (of course) Killing Demigods. Even though you hit like a truck designed by Cthulhu (which, clearly, is better than your average truck), so does everyone else so killing your opponents can be a feat. Usually even if you get the upper hand, they've got enough speed stuff to get away from you and back to the health crystal before you can finish a sneeze (or a one second ability cast), so downing an opponent means good teamwork. If you're evenly matched in skill (and relatively matched in items), you won't kill someone in 1v1 and they won't kill you. So you need a skilled partner. The real magic happens in 2v2's and larger melees because then you really see teamwork with stuns, heals, shields, and so forth make a huge difference. Even when everything goes right, you still might not get a kill.
(5) Getting giants. A creep wave with giants on strong setting with a demigod in their midst is going to hurt like nothing else.
(6) Speed and response time. Everything's moving faster (even though game speed is on normal) because so much more damage is being done. When a threat appears somewhere on the map that you're not, you need to know how you're going to get there in time to prevent them from knocking down 4 or 5 towers and grabbing all the flags along the way.
An example of fun: earlier today I was playing as UB in this mode, and after fifteen minutes or so had a mageslayer, slayer's gloves, bracelets of wrath, and ashkandor along with some lesser items. I was clearing some towers near a cooldown flag, and scored a crit on a regular attack on a tower with beastial wrath and bracelets of wrath turned on for 12,000. That's not a typo. Not twelve hundred, but twelve thousand. I had 32% life steal from items, so that hit healed me for 3840. Now imagine other demigods running around with comparable power and you get the idea.