I am currently attempting to create a campaign, inspired both by West Marches, and earlier editions of D&D (mostly OD&D and 1e AD&D), but still keeping the 5e rules that my group are familiar with.
One of the ideas I have had to get the 'deadly' feel of those earlier editions is to remove the death saving throw system and just have characters die when they drop to 0 hp. Newly rolled up characters would of course start at level 1.
I started my current, ongoing 5e campaign at level 5, as the players said that they didn't want to slog through the early levels (as we had done in 4e). As a result, I have little idea of how deadly the game is (RAW) at the lower levels.
Could someone with experience of lower level play tell me what the effect of this house-rule would be? How often do 1st and 2nd level characters drop to 0 hp? Essentially, could a careful party survive and succeed at low levels with this change, or are encounters in 5e designed too much around the idea of death saving throws (resulting in too many deaths and TPKs)?
Brief Summary of How Encounters are Contructed in West Marches
West Marches is essentially a sandbox hex-crawl. Encounters are rolled for every x period of time, based on environment, how well the PCs are keeping watch, etc. The roll tables include a huge range of encounter CRs. However, the chances are weighed heavily in favour of lower CR fights rather than higher CR ones (i.e. you're more likely to be attacked by a wolf than a dragon). This means that the random encounters will, for the most part, be below the CR of the party.
Encounters tied to goals (dungeons, etc.) could be of the PC's CR, or higher, but it is their choice to face these challenges. The PCs can go anywhere, do anything, so they can wait until they feel ready to face any particular threat.
Finally, the PCs are encouraged to think of creative solutions to problems. You might roll up d4 men at arms on a roll table; this does not mean that 3 men come running at them to attack, instead, it could mean that 3 men are arguing over a cart of gold. The PCs could decide to attack, and steal the gold, but that would be their decision. Non-combat approaches to encounters are normally possible.
What is the West Marches?
The West Marches is a style of campaign in which there is little to no over-arching plot, just over-arching environment. The campaign has around 10 to 20 players. Groups of 4-6 form from this pool and approach the DM (me) with a certain goal in mind (e.g. investigate the tower).
It is expected that characters will die in combat (either through bad luck, or bad planning), and as a result, backstory and character plot hooks (etc.) are kept to a minumum. Instead, players discover who their characters are as they play. Characters are memorable not for what they did before arriving in the West Marches, but for what they have done in the West Marches.
Hopefully that proves useful to people wanting to answer in context, but without reading the link (as SevenSidedDie suggested).