diff --git a/config.lua b/config.lua
index 659adac..a128f83 100644
--- a/config.lua
+++ b/config.lua
@@ -1,7 +1,7 @@
 local preset = rawget(_G, 'preset')
 preset = preset ~= nil and preset ~= '' and preset or 'ars'
 
-local common_cfg = {
+local defaults = {
     -- read-only modes:
     playable_mode = false,
     playback_mode = false,
@@ -45,6 +45,7 @@ local common_cfg = {
     deviation = 1.0,
     unperturbed_trial = true, -- perform an extra trial without any noise.
                               -- this is good for logging, so i'd recommend it.
+    epoch_trials = 50,
     graycode = false, -- for ARS.
     negate_trials = true, -- try pairs of normal and negated noise directions.
     -- AKA antithetic sampling. note that this doubles the number of trials.
@@ -57,173 +58,23 @@ local common_cfg = {
     sigma_decay = 0.0, -- for SNES, xNES.
 }
 
-local cfg
-if preset == 'snes' then
-
-    cfg = {
-        es = 'snes',
-
-        log_fn = 'logs-snes.csv',
-        params_fn = 'params-snes.txt',
-
-        starting_lives = 1,
-        min_time = 300,
-        timer_loser = 1.0,
-
-        epoch_trials = 100,
-        negate_trials = false,
-
-        deviation = 1.0,
-        min_refresh = 0.2,
-
-        param_rate = 0.5,
-        sigma_rate = 0.1,
-        param_decay = 0.02, -- note: multiplied by its std, and param_rate.
-        sigma_decay = 0.01, -- note: multiplied by sigma_rate.
-    }
-
-elseif preset == 'snes2' then
-
-    cfg = {
-        es = 'snes',
-
-        log_fn = 'logs-snes2.csv',
-        params_fn = 'params-snes2.txt',
-
-        start_big = true,
-        min_time = 300,
-        timer_loser = 1.0,
-
-        score_multiplier = 0,
-
-        init_zeros = true,
-
-        reduce_tiles = true,
-        bias_out = false,
-
-        deterministic = false,
-
-        deviation = 0.5,
-        negate_trials = false,
-        min_refresh = 0.5,
-
-        epoch_trials = 100,
-
-        param_rate = 1.0,
-        sigma_rate = 0.01,
-        param_decay = 0.02,
-        sigma_decay = 0.01,
-    }
-
-elseif preset == 'xnes' then
-
-    cfg = {
-        es = 'xnes',
-
-        log_fn = 'logs-xnes.csv',
-        params_fn = 'params-xnes.txt',
-
-        start_big = true,
-        min_time = 300,
-        timer_loser = 1.0,
-
-        score_multiplier = 0,
-
-        init_zeros = true,
-
-        reduce_tiles = true,
-        bias_out = false,
-
-        deterministic = false,
-
-        deviation = 0.5,
-        negate_trials = false,
-
-        epoch_trials = 50,
-
-        param_rate = 1.0,
-        sigma_rate = 0.01,
-        covar_rate = 0.01,
-    }
-
-elseif preset == 'xnes2' then
-
-    cfg = {
-        es = 'xnes',
-
-        log_fn = 'logs-xnes2.csv',
-        params_fn = 'params-xnes2.txt',
-
-        start_big = true,
-        min_time = 300,
-        timer_loser = 1.0,
-
-        score_multiplier = 0,
-
-        init_zeros = true,
-
-        reduce_tiles = true,
-        bias_out = false,
-
-        deterministic = false,
-
-        deviation = 1.0,
-        negate_trials = true, --false,
-
-        epoch_trials = 10, --50,
-
-        param_rate = 0.5,
-        sigma_rate = 0.04,
-        covar_rate = 0.04,
-        param_decay = 0.004,
-        sigma_decay = 0.00128,
-    }
-
-elseif preset == 'ars' then
-
-    cfg = {
-        es = 'ars',
-        epoch_top_trials = 20 * 2,
-        ars_lips = false,
-
-        log_fn = 'logs-ars.csv',
-        params_fn = 'params-ars.txt',
-
-        start_big = true,
-        min_time = 300,
-        timer_loser = 1.0,
-
-        bias_out = false,
-
-        deterministic = false,
-
-        graycode = false,
-        deviation = 0.1,
-        negate_trials = false,
-
-        epoch_trials = 25 * 2,
-
-        param_rate = 1.0,
-        param_decay = 0.0025,
-    }
-
-elseif preset == 'play' then
-
-    cfg = {
-        playable_mode = true,
-    }
-
-else
-
-    error("invalid preset: "..tostring(preset))
+local presets = require("presets")
 
+for _, cfg in pairs(presets) do
+    local parent = defaults
+    if cfg.parent ~= nil then
+        parent = presets[cfg.parent]
+        assert(parent, "no such parent preset: "..tostring(cfg.parent))
+    end
+    setmetatable(cfg, {__index=parent})
 end
 
+local cfg = presets[preset]
+assert(cfg, "invalid preset: "..tostring(preset))
+
 -- TODO: so, uhh..
 -- what happens when playback_mode is true but unperturbed_trial is false?
 
-setmetatable(cfg, {__index=common_cfg}) -- gets overridden later.
-
 if cfg.es == 'ars' then
     if cfg.param_rate == nil then cfg.param_rate = cfg.base_rate end
 else
@@ -232,9 +83,12 @@ end
 if cfg.sigma_rate == nil then cfg.sigma_rate = cfg.base_rate end
 if cfg.covar_rate == nil then cfg.covar_rate = cfg.sigma_rate end
 
+local parent = getmetatable(cfg).__index
+
 setmetatable(cfg, {
     __index = function(t, n)
-        if common_cfg[n] ~= nil then return common_cfg[n] end
+        if parent ~= nil and parent[n] ~= nil then return parent[n] end
+        if n == 'name' then return nil end
         if n == 'log_fn' then return nil end
         if n == 'params_fn' then return nil end
         if n == 'stats_fn' then return nil end
diff --git a/presets.lua b/presets.lua
new file mode 100644
index 0000000..01e7e90
--- /dev/null
+++ b/presets.lua
@@ -0,0 +1,190 @@
+-- these are all still very experimental,
+-- but they should at least give you a head-start.
+local presets = {}
+
+local function make_preset(cfg)
+    local name = cfg.name
+    if name ~= nil then
+        cfg.log_fn = cfg.log_fn or 'logs-'..name..'.csv'
+        cfg.params_fn = cfg.params_fn or 'params-'..name..'.txt'
+    end
+    presets[name] = cfg
+    return cfg
+end
+
+make_preset{
+    name = 'snes',
+
+    es = 'snes',
+
+    starting_lives = 1,
+    min_time = 300,
+    timer_loser = 1.0,
+
+    epoch_trials = 100,
+    negate_trials = false,
+
+    deviation = 1.0,
+    min_refresh = 0.2,
+
+    param_rate = 0.5,
+    sigma_rate = 0.1,
+    param_decay = 0.02,
+    sigma_decay = 0.01,
+}
+
+make_preset{
+    name = 'snes2',
+
+    es = 'snes',
+
+    start_big = true,
+    min_time = 300,
+    timer_loser = 1.0,
+
+    score_multiplier = 0,
+
+    init_zeros = true,
+
+    reduce_tiles = true,
+    bias_out = false,
+
+    deterministic = false,
+
+    deviation = 0.5,
+    negate_trials = false,
+    min_refresh = 0.5,
+
+    epoch_trials = 100,
+
+    param_rate = 1.0,
+    sigma_rate = 0.01,
+    param_decay = 0.02,
+    sigma_decay = 0.01,
+}
+
+make_preset{
+    name = 'xnes',
+
+    es = 'xnes',
+
+    start_big = true,
+    min_time = 300,
+    timer_loser = 1.0,
+
+    score_multiplier = 0,
+
+    init_zeros = true,
+
+    reduce_tiles = true,
+    bias_out = false,
+
+    deterministic = false,
+
+    deviation = 0.5,
+    negate_trials = false,
+
+    epoch_trials = 50,
+
+    param_rate = 1.0,
+    sigma_rate = 0.01,
+    covar_rate = 0.01,
+}
+
+make_preset{
+    name = 'xnes2',
+
+    es = 'xnes',
+
+    log_fn = 'logs-xnes4.csv',
+    params_fn = 'params-xnes4.txt',
+
+    start_big = true,
+    min_time = 300,
+    timer_loser = 1.0,
+
+    score_multiplier = 0,
+
+    init_zeros = true,
+
+    reduce_tiles = true,
+    bias_out = false,
+
+    deterministic = false,
+
+    deviation = 1.0,
+    negate_trials = true, --false,
+
+    epoch_trials = 10, --50,
+
+    param_rate = 0.5,
+    sigma_rate = 0.04,
+    covar_rate = 0.04,
+    param_decay = 0.004,
+    sigma_decay = 0.00128,
+}
+
+make_preset{
+    name = 'xnes3',
+
+    es = 'xnes',
+
+    log_fn = 'logs-xnes5b.csv',
+    params_fn = 'params-xnes5b.txt',
+
+    start_big = true,
+    timer_loser = 1.0,
+
+    score_multiplier = 0,
+
+    init_zeros = true,
+
+    reduce_tiles = true,
+    bias_out = false,
+
+    deterministic = false,
+
+    deviation = 0.1207,
+    negate_trials = true,
+
+    epoch_trials = 10,
+
+    param_rate = 0.5,
+    sigma_rate = 0.16,
+    covar_rate = 0.04,
+    param_decay = 0.004, -- this should be ok now that it's mul by sigma.
+    sigma_decay = 0.00128, -- this might be okay... but watch out.
+}
+
+make_preset{
+    name = 'ars',
+
+    es = 'ars',
+    epoch_top_trials = 20 * 2,
+    ars_lips = false,
+
+    start_big = true,
+    min_time = 300,
+    timer_loser = 1.0,
+
+    bias_out = false,
+
+    deterministic = false,
+
+    graycode = false,
+    deviation = 0.1,
+    negate_trials = false,
+
+    epoch_trials = 25 * 2,
+
+    param_rate = 1.0,
+    param_decay = 0.0025,
+}
+
+make_preset{
+    name = 'play',
+
+    playable_mode = true,
+}
+
+return presets