Fixed incompatible tag comparisons, added two simple mods

mods/character-movesets.lua

@@ -30,7 +30,7 @@ function luigi_before_phys_step(m)
 
     -- faster swimming
     if (m.action & ACT_FLAG_SWIMMING) ~= 0 then
-        hScale = hScale * 1.25
+        hScale = hScale * 1.5
     end
 
     -- slower holding item

mods/faster-swimming.lua

@@ -0,0 +1,21 @@
+-- name: Faster Swimming
+-- incompatible:
+-- description: Everyone swims faster.
+
+function mario_before_phys_step(m)
+    local hScale = 1.0
+
+    -- faster swimming
+    if (m.action & ACT_FLAG_SWIMMING) ~= 0 then
+        hScale = hScale * 2
+    end
+
+    m.vel.x = m.vel.x * hScale
+    m.vel.z = m.vel.z * hScale
+end
+
+-----------
+-- hooks --
+-----------
+
+hook_event(HOOK_BEFORE_PHYS_STEP, mario_before_phys_step)

mods/low-gravity.lua

@@ -0,0 +1,15 @@
+-- name: Low Gravity
+-- incompatible:
+-- description: Gives everyone low gravity
+
+function mario_update(m)
+    if (m.action & ACT_FLAG_AIR) ~= 0 then
+        m.vel.y = m.vel.y + 1
+    end
+end
+
+-----------
+-- hooks --
+-----------
+
+hook_event(HOOK_MARIO_UPDATE, mario_update)

src/pc/mod_list.c

@@ -203,6 +203,9 @@ static bool mod_list_incompatible_match(struct ModListEntry* a, struct ModListEn
     if (a->incompatible == NULL || b->incompatible == NULL) {
         return false;
     }
+    if (strlen(a->incompatible) == 0 || strlen(b->incompatible) == 0) {
+        return false;
+    }
 
     char* ai = a->incompatible;
     char* bi = b->incompatible;