Minor fixes.

main.rb

@@ -10,17 +10,16 @@ require "zlib"
 ALPHANUM = [*"0".."9", *"A".."Z", *"a".."z", "-", "_"].freeze
 
 env_data = File.exist?(".env") ? File.read(".env") : ""
-ENV_HASH = {}
 
 env_data.each_line do |line|
   next unless (match = line.match(/^([A-Z_][A-Z0-9_]*)=(.*)$/))
-  ENV_HASH[match[1]] = match[2]
+  ENV[match[1]] = match[2]
 end
 
 load "logman.rb"
-# Logman.log ENV_HASH.inspect
+# Logman.log ENV.inspect
 
-db_file = File.expand_path("infinsweeper.db", __dir__)
+db_file = ENV.fetch("INFINSWEEPER_DB", File.expand_path("infinsweeper.db", __dir__))
 DB = Sequel.connect("sqlite:///#{db_file}", single_threaded: false)
 DB.run("PRAGMA foreign_keys = ON;")
 DB.create_table? :Players do