Going All The Way (updated 13/4/19)

Update: Quillax levelled up to 20 today, 13/4/2019!

As GM I've had 2 5e PCs reach level 20 (I mostly do individual XP); only one (now two) from 1st - in my Wilderlands 5e game Hakeem the Barbarian got from level 1 (March 20th 2015) to level 20 (September 15th 2017) in 132 online sessions, about the same as 66 offline sessions, over two and a half years. Played on a bit after that with Epic Boons.

In my tabletop 5e Runelords game Quillax the Druid got from level 1 (November 2015) to 18 (end October 2017) in 2 years and 64 tabletop sessions each of around 4-5 hours; we recently restarted as an online game now Quillax's player is a globetrotter - http://smonscurseofthecrimsonthrone.blogspot.com/ - so could make 20 yet! 
Update: After resuming play & 12 online sessions, reached 20th on 13/4/19.

But I've also had 60-80 session campaigns with no PCs getting over level 10. In my 4e Loudwater game http://frloudwater.blogspot.com/ Lirael the Ranger went 1st (ca April 2011) to 30th (August 2016) in 103 tabletop sessions and something over 5 years of play; she reached level 20 in session 71 - http://frloudwater.blogspot.com/2014/07/session-71-17-1811483-remorhaz-tower.html - July 2014, so a bit over 3 years. That was a 'party XP' game.

Lirael, Queen of the Shining Vale, Ranger-30 (4e D&D)

Hakeem the Destroyer, Barbarian-20

   

Quillax, Warden of Jorgenfist  (Druid-20) may look a bit like this.

Shieldbiter, Barbarian-20 (from 10th).

My new XP system

I'm about to start two new 5e campaigns, and I decided to use a completely different XP system, almost identical. Basically the idea is 1 XP per significant encounter or achievement, such as a quest completion or big treasure haul, 2-3 XP in exceptional cases.

1. For Princes of the Apocalypse running for ca 5 hours 1/4 weeks, initially 5 XP 1st to 2nd and 2nd to 3rd, then 10 XP/level.
2. For Primeval Thule running for ca 3.5 hours 1/2 weeks , a flat 10 XP per level, but I am giving PCs a hit point kicker at 1st level (hp = full CON + max hd, rather than max hd plus CON bonus) so they can stay at 1st level for longer.

This will resemble the fiat 'milestone levelling' suggested method, but I wanted a bit more structure than that, and one better suited to sandboxy play. I'm looking for about 2-3 sessions of play per level (10 XP), which is the 5e DMG suggested rate, but much faster than in my current 5e games, which use the standard XP rules.

Discussion here

Uncertainty in RPG Worlds

Uncertainty - where even the GM does not know, has not defined, the truth of the matter.
I find this dramatically very powerful.
For instance, in my Wilderlands, two young lovers, Cassandra the Druidess & Polyachus the Apollo priest, both fairly major NPCs. and Cassandra a very long term NPC from a previous campaign, had taken shelter on a remote island to escape the evil Archmage Oriax. Unfortunately that island was later occupied by evil Skandik pirates, and it was assumed the lovers had met a terrible fate. But when the Skandiks had left, and others arrived on the island, they found only beautiful songbirds, never seen before. The legend grew up that the gods had taken pity on the lovers and transformed them into birds, and the birds now seen on the isle are their offspring.
I have no intention of ever proclaiming - or deciding - a definitive truth of the matter.
I do this with other Big Mysteries of the campaign, such as whether or not the gods really exist. I have my suspicions, but have no intention of forming a definitive answer.
I find this approach makes the campaign world feel much more real to me. I've noticed that some other designers use this sort of ambiguity, eg in the Elder Scrolls CRPGs, as a way to create depth and mystery.
Anyone else do this? Is it a common practice?

5e - Slowing advancement after Level 10

The 5e XP table is designed to speed up advancement after level 10. Discussion on doing the opposite here for a megadungeon sandbox campaign with PCs of various levels. Conclusion is that simply halving XP awards to level 11+ PCs should work best, giving the following effective requirements:

10 to 11: 21000 > 21,000 XP as per RAW
11  to 12:15000 > 30,000
12 to 13   20000 > 40,000
13  to 14  20000 > 40,000
14 to 15   25000 > 50,000
15 to 16   30000 > 60,000
16 to 17   30000 > 60,000
17 to 18   40000 > 80,000
18 to 19   40000 > 80,000
19 to 20   50000 > 100,000

Going Epic-10 in 5e D&D

I suggest to DMs that if they are running a story-based, low combat game in a lowish-fantasy setting, then go “E10” – levels should be capped at 10 not 20, and use the Epic rules in the DMG from 10th level: every 30,000 XP above level 10, a PC either gains +2 attribute (I’d retain cap at 20, maybe 22); or if the game uses Feats the PC can gain a Feat of the player's choice.

Character Advancement
Experience Points Level Proficiency Bonus
0                               1                +2
300                           2                +2
900                           3                +2
2,700                        4                +2
6,500                        5                +3
14,000                      6                +3
23,000                      7                +3
34,000                      8                +3
48,000                      9                +4
64,000                    10                +4
94,000                    E1               +4
124,000                  E2               +4
154,000                  E3               +4
+30,000                  +1               +4

Edit: The Primeval Thule 5e setting seems particularly suitable for this approach.

A Fighter Attacks house rule for OD&D to 1e/2e AD&D

I don't much like the Fighter ability to get his level in attacks/round vs 1 hd (or 0-level in 1e) foes, since it requires the GM to tell the player how many hd the enemy have, or the player has to constantly ask. It's also a bit silly at higher level IMO. But without some kind of multi attack Fighters can be seriously underpowered at higher level. I'm also not a fan of weapon specialisation bonuses to hit & damage, they change the balance of weapons and make two-handed high damage weapons underpowered; it also favours missile weapons with a high attack rate.

Somewhat influenced by 5e's insight that you can give staggered attacks/round bonuses to fighters without breaking the game (in 5e at 5th, 11th & 20th) matching where other classes like wizard/MU get big spell boosts, and wanting to restore the importance of Hero (4th) & Supehero (8th) levels, I came up with the following, specifically for my Swords & Wizardry game but it should work in all pre-3e D&D, especially if 18%-strength is not in play - so ideal for OD&D and BX-BECMI.

Fighters get +1 attack to the weapon normal attack rate at the following levels: 2nd, 4th & 8th. For melee weapons this gives an attack rate as follows:

Fighter
Level #Attacks
1 1
2-3 2
4-7 3
8+ 4

Fighter subclasses such as Paladin & Ranger (& Cavalier, Barbarian etc) get bonus attacks at 4th & 8th only, giving the following attack rates for melee weapons

Paladin & Ranger
Level #Attacks
1-3 1
4-7 2
8+ 3

So far this seems to work really well. I've tweaked Ranger bonus damage vs giant class creatures to take account of the increased number of attacks:

Ranger Level 1-5 Bonus damage +1/level
Ranger Level 6-15 Bonus damage +1/2 levels:
Level Bonus
7 +6
9 +7
11 +8
13 +9
15 +10 (max)

MUs and Thieves get +1 attack at 8th.
Clerics get +1 attack at 7th.

Update: polite, intelligent conversation here. :D

Running O5R - OSR in 5e

"Hello, my friend! If you seek knowledge about mighty Talos er running OSR in 5e, you have most certainly come to the right person."

Things to be aware of:

5e is a loose enough system that you don't really need to worry about balance any more than you would when running an OSR system. Players should know that running away is an option, and the GM should normally make this possible, possibly with some Athletics and/or Stealth checks to evade pursuit.

1. Generally you should just use the 5e monster stats. Some 5e monsters are a bit tougher than in OSR, eg orcs, some are weaker, eg manticores. But overall it works fine.
2. For monsters that don't exist in 5e, you can either use the closest 5e equivalent (tweaking a bit, especially any special powers) or convert the stats. For converting BFRPG to 5e I recommend:

AC: deduct 1 from the BFRPG AC since it starts at 11.
Hit Points: Usually doubling the BFRPG/OD&D hp works
Damage: Usually should be about double BFRPG number. You can often get this by keeping the BFRPG damage dice and adding an attribute bonus
CR: I pretty much eyeball CR, but halving the hit dice probably gives a reasonable number.
Attributes: One pretty much has to eyeball these with reference to 5e norms, eg low level monsters typically have a +1 to +3 attribute bonus for their attack attribute, mid level +4 to +6 (NPCs usually cap at +5/attribute 20), high level +7 to +9, rarely +10 (needs a 30 Attribute).
Attack Score & Magic Save DC can be calculated off CR & Attribute bonus, the totals should typically be around +4/DC 12 at low level, +7/DC 15 at medium level, +10/DC 18 at high level.

Monster numbers: 5e monsters can be more dangerous in large groups, though I've not found it a big enough issue to worry about generally. Most BFRPG adventures don't need numbers adjusting IMO, but Chris Gonnerman (Morgansfort) has a tendency to put 28 kobolds in a room, in a 1st level adventure. You may want to simply halve his monster numbers where they look excessive - but I'm running it in Swords & Wizardry and doing that, it's not a 5e thing so much as a designer thing.

I always use the Basic D&D 2d6 Reaction & Morale rules, I'd recommend using those or similar.

Treasure: I don't normally alter the BX/BFRPG listed treasure values unless I also reduced monster numbers (eg halve monsters, halve treasure). The main thing is don't assume the PCs will find the treasure, it should be an uncertain reward. It won't break the game if they are successful and find lots of treasure. Just don't let them buy unlimited magic items from the DMG, 5e isn't designed to support that. A limited list of Common & Uncommon items at twice creation cost is fine, eg I have a list of Uncommon items the PCs can purchase at 1000gp each. Likewise if you allow magic item creation at list price, enforce crafting time, level limits, formulae etc so they are encouraged to focus on the cheaper, easier stuff.

Aside from magic items, it's great IMO if the PCs find lots of treasure and are motivated to do interesting things with it. It definitely won't break the game (or any edition of D&D except 3e/PF, really).